Elastic Compute Service:Instance FAQ

How do I check which instance types are available for purchase within a specific region or zone?

You can go to the ECS Instance Types Available for Each Region page to view the instance types available in each region.

What do I do if resources are sold out when I attempt to purchase an instance within a specific region or zone?

Instance resources are dynamic. Alibaba Cloud replenishes as appropriate the resources that are insufficient. If the resources that you want to purchase are still unavailable after you take all of the preceding measures, try again later.

How do I select an instance type that is suitable for my business?

Consider the following factors when you select an instance type. For more information about how to select an instance type, see Best practices for instance type selection.

• Your business needs
• Your website type
• The average number of page views per day on your website
• The size of your homepage
• The data capacity of your website

How long does it take to create an ECS instance?

I paid for an instance but no instance was created. Why?

If resources within the specified zone are insufficient to create an instance of your selected instance type, the instance cannot be created. A refund is automatically credited to your account. If you do not receive a refund within half an hour, submit a ticket.

You can go to the ECS Instance Types Available for Each Region page to view the instance types available in each region.

Why does a purchased instance have a memory size different from that defined in the instance type?

The memory size defined in each instance type is the total memory size, which includes the amount of memory occupied by the system, such as BIOS reserved memory and memory overheads for running the kernel and the hypervisor. As a result, the size of available memory on your instance is smaller than the memory size defined in the instance type. Different instance families may use different technology stacks, which causes the percentage of memory occupied by the system to vary slightly.

What are enterprise-level instances? What are shared instances?

Enterprise-level instances belong to a series of instance families that have been released by Alibaba Cloud since September 2016. Enterprise-level instances provide high performance, consistent computing power, and balanced network performance. Enterprise-level instances have exclusive and consistent computing, storage, and network resources, and are suitable for enterprise scenarios that require high business stability.

Shared instances belong to a series of instance families that are intended for individuals or small and medium-sized websites. Shared instances share resources, in contrast with enterprise-level instances that each have their own resources exclusively. As a result, shared instances do not provide consistent computing performance, but cost less.

What are the differences between enterprise-level and shared instances?

Enterprise-level instances use a CPU-bound scheduling scheme. Each vCPU is bound to a CPU hyperthread. Instances do not compete for CPU resources and do provide consistent computing performance as specified in the service-level agreement (SLA).

Shared instances use a CPU-unbound scheduling scheme. Each vCPU is randomly allocated to an idle CPU hyperthread. vCPUs of different instances compete for CPU resources, which causes computing performance to fluctuate when traffic loads are heavy. Shared instances can guarantee availability as specified in the SLA but not performance.

Which instance families are enterprise-level instance families? Which instance families are shared instance families?

Among the instance families that are available for purchase, t6, t5, s6, n4, mn4, xn4, and e4 are shared instance families, and the rest are enterprise-level instance families.

In what business scenarios do I need to purchase enterprise-level instances?

For business scenarios for which different enterprise-level instances are suitable, see Overview of instance families and Best practices for instance type selection.

How is the network performance of enterprise-level instances?

The network performance of enterprise-level instances depends on their specifications. The higher their specifications are, the higher network performance the instances can deliver. For more information about the network performance of different instance types, see Overview of instance families.

Which disk categories do enterprise-level instances support?

For information about the disk categories that enterprise-level instances support, see Disk categories.

Which image types do enterprise-level instances support?

For information about the public images that enterprise-level instances support, see Overview.

You can also import custom images. For more information, see Import a custom image.

What are the limits on changing the instance types of enterprise-level instances?

For information about the limits on changing the instance types of enterprise-level instances, see Instance families that support instance type changes.

Can I change a shared instance into an enterprise-level instance?

For more information, see Instance families that support instance type changes.

What characteristics do persistent memory-optimized instances have?

What requirements do persistent memory-optimized instances have for operating systems?

Alibaba Cloud provides support for Alibaba Cloud Linux 2. Alibaba Cloud Linux 2 integrates tools for scenarios to which persistent memory is applicable to work out of the box. In some scenarios such as those in which Redis applications are used, Alibaba Cloud Linux 2 outperforms community-supported Linux distributions by 20% in terms of performance.

After I purchase a persistent memory-optimized instance, how do I configure its persistent memory as memory?

You can use tools to configure the persistent memory as memory. For more information, see Configure the usage mode of persistent memory.

When persistent memory is being used as memory on persistent memory-optimized instances, can I deploy and run Redis applications on the instances?

You can significantly reduce the TCO per GiB of memory for Redis applications by running them on persistent memory-optimized instances. To ensure performance, you must modify the Redis applications by stratifying their data and storing the data in different types of memory. You can store non-hot data in persistent memory and hot data in regular memory.

I already have a Redis cluster that is based on regular memory and want to migrate business from this cluster to persistent memory-optimized instances. How do I do this? What items do I need to take note of?

You must ensure business consistency and data reliability while you are migrating business from the Redis cluster to persistent memory-optimized instances. We recommend that you first purchase a single persistent memory-optimized instance and test it with a small amount of required business to check whether the basic performance and capacity model of the instance meet your business requirements. If the basic performance and capacity model of the instance meet your business requirements, you can scale out to more persistent memory-optimized instances and take over business from the entire Redis cluster.

Can I deploy and run a parameter server (PS) architecture on persistent memory-optimized instances whose persistent memory is used as memory?

Server nodes in a PS architecture store all training parameters of training clusters, traditionally in their memory. These parameters consume a large amount of memory and are expensive to store. When you run a PS architecture on persistent memory-optimized instances whose persistent memory is used as memory, we recommend that you store all parameters in persistent memory and only hash tables in regular memory. This way, you can significantly reduce the TCO of training clusters.

You can modify the applications to suit your business requirements, or submit a ticket to contact Alibaba Cloud technical support.

After I purchase a persistent memory-optimized instance, how do I configure its persistent memory as local disks?

You can use tools to configure the persistent memory as local disks. For more information, see Configure the usage mode of persistent memory.

To which applications are local disks that can deliver higher performance applicable?

Can I deploy Redis or MySQL applications on persistent memory-optimized instances whose persistent memory is used as local disks? Do the applications need to be modified in the same manner as they do when persistent memory is used as memory?

Yes, you can deploy Redis and MySQL applications on persistent memory-optimized instances whose persistent memory is used as local disks. You do not need to modify these applications before they can recognize the persistent memory as standard SSDs.

How is the performance of persistent memory used as local disks, compared with local non-volatile memory express (NVMe) SSDs and cloud disks?

How reliable is persistent memory?

The reliability of data stored in persistent memory depends on the reliability of persistent memory devices and the physical servers to which these devices are attached. Risks of single points of failure exist. To ensure the reliability of application data, we recommend that you implement data redundancy at the application layer and use cloud disks for long-term data storage.

When persistent memory-optimized instances are released, data stored in their persistent memory is automatically cleared. We recommend that you back up data before you release the instances. It takes longer to release persistent memory-optimized instances than to release other types of instances.

What are the differences between ECS bare metal instances, traditional cloud hosts (virtual machines), and traditional physical machines?

For information about the differences, see Overview.

How is the network performance of ECS bare metal instances?

The network performance of ECS bare metal instances depends on their specifications. The higher their specifications are, the higher network performance the instances can deliver. For more information about the network performance of different ECS Bare Metal Instance types, see Overview of instance families.

Which disk categories do ECS bare metal instances support? How many data disks can be attached to a single ECS bare metal instance?

ECS bare metal instances support ultra disks, standard SSDs, and enhanced SSDs (ESSDs). Up to 16 data disks can be attached to a single ECS bare metal instance.

Can the configurations of ECS bare metal instances be upgraded or downgraded? Do the instances support failover?

The configurations of ECS bare metal instances cannot be upgraded or downgraded. The instances do support failover. When the physical machine that hosts an ECS bare metal instance fails, the instance is failed over. Data is retained in the data disks of the instance.

How do I create an SCC instance?

How are SCC instances billed?

SCC instances can be billed on a weekly, monthly, or yearly subscription basis.

How do I create an SCC by using E-HPC?

You can log on to the E-HPC console or call the CreateCluster operation to create an SCC.

How do I use SCC RDMA?

When you create an SCC instance, select an image that is customized for SCC. The image supports RDMA RoCE drivers and OFED stacks. Then, you can use SCC RDMA by virtue of the IB verbs API or implement RDMA-based communication by using the MPI.

Which instance types support preemptible instances?

Instance types that support pay-as-you-go instances also support preemptible instances. If a preemptible instance of a specific instance type cannot be created due to insufficient resources, try another instance type.

In which regions can I create preemptible instances?

Preemptible instances can be created within all Alibaba Cloud regions. If preemptible instances cannot be created within a specific region due to insufficient resources, try another region.

When I attempt to purchase an ECS instance, the Preemptible Instance option is unavailable on the instance buy page. Why?

The availability of the Preemptible Instance option depends on your ECS usage. The Preemptible Instance option is available only to authorized users.

How do I bid for a preemptible instance?

To create a preemptible instance, you must specify a maximum hourly price to bid for spare resources of an instance type. If the spot price (current market price per hour) of the instance type does not exceed your specified maximum hourly price, the preemptible instance is created and billed based on the spot price. For more information, see Create a preemptible instance.

What is the relationship between the user-defined maximum hourly price and the spot price of a preemptible instance?

If the spot price does not exceed the user-defined maximum hourly price, the preemptible instance is created and billed based on the spot price. After a preemptible instance is created, it enters a protection period during which it cannot be automatically released due to insufficient resources or fluctuations in the spot price.

After the protection period ends, the system checks the spot price and resource availability of the instance type every 5 minutes. If the spot price exceeds the user-defined maximum hourly price or if resources for the instance type are insufficient, the preemptible instance that is in the Running state is released.

Can I view the spot price of an instance type when I purchase a preemptible instance?

Yes, when you create a preemptible instance in the ECS console, you can view the spot price and price history of each selected instance type. The total instance price includes fees for the instance type, storage, and bandwidth and is displayed in the lower part of the instance buy page. The instance type fee is the spot price of the selected instance type.

Can I view the price history of a preemptible instance type? How?

Yes, you can select an instance type to view its price history when you attempt to create a preemptible instance in the ECS console. You can also call the DescribeSpotPriceHistory operation to view the price history of a preemptible instance type.

How many preemptible instances can be purchased by a single account?

vCPU-based quotas apply to preemptible instances within each account, whereas instance-based quotas do not. When you create a preemptible instance, you can view the available vCPU-based quota after you select an instance type. For more information, see the "Instance limits" section in Limits.

How do I increase my vCPU-based quotas?

To increase your vCPU-based quotas, submit a ticket.

Can preemptible instances be converted into subscription instances?

No, preemptible instances cannot be converted into subscription instances.

Can the instance type of a preemptible instance be changed?

No, the instance types of preemptible instances cannot be changed.

A preemptible instance does not meet my requirements. How do I upgrade it to a higher-specification instance type at a low cost?

The instance types of preemptible instances cannot be changed. We recommend that you create a custom image based on the system disk of your preemptible instance and then use the custom image to create a preemptible instance of a higher-specification instance type. For more information, see Create a custom image from a snapshot and Create an ECS instance by using a custom image.

If I select Use Automatic Bid (SpotAsPriceGo) when I create a preemptible instance, will the created instance be automatically released due to insufficient resources?

When you select Use Automatic Bid (SpotAsPriceGo), the spot price is used as the bid price and can raise as high as the pay-as-you-go price for the selected instance type. This ensures that the created preemptible instance will not be automatically released due to fluctuations in the spot price. However, the instance may still be automatically released due to insufficient resources for the instance type.

If I set the maximum hourly price to the pay-as-you-go price for the selected instance type when I create a preemptible instance, may the instance be automatically released?

You can set the maximum hourly price to the pay-as-you-go price for your selected instance when you create a preemptible instance. This ensures that the created instance will not be automatically released due to fluctuations in the spot price. However, the instance may still be automatically released due to insufficient resources for the instance type.

Can I cancel or reschedule the automatic release of a preemptible instance?

Yes, you can cancel or reschedule the automatic release of your preemptible instance anytime because the instance is released.

I do not have overdue payments in my account. Why have my preemptible instances been released?

After the protection period of a preemptible instance ends, if the spot price exceeds the user-defined maximum hourly price or if resources are insufficient, the instance is automatically released.

How are release rates on the instance buy page calculated? Why are most of them in the range of 0% to 3%?

Release rates vary based on zones and instance types. The single-day release rate of an instance type within a zone is calculated based on the following formula: Single-day number of released preemptible instances/Single-day total number of preemptible instances. Most release rates are in the range of 0% to 3% as expected. Alibaba Cloud continues our efforts to reduce release rates and ensure higher availability of your preemptible instances.

Am I notified when my preemptible instances are about to be released? How am I notified?

Yes, you are notified when your preemptible instances are about to be released. When your preemptible instance needs to be released due to a spot price change or insufficient resources, the instance first enters the To Be Released state and is automatically released in 5 minutes.

You can use CloudMonitor to subscribe to notifications for interrupted preemptible instances. For more information, see Configure event notifications.

To check whether an instance is in the To Be Released state, you can view the instance metadata, or call the DescribeInstances operation and view the returned OperationLocks data. For more information, see Overview of ECS instance metadata and DescribeInstances.

Can the data of a preemptible instance be automatically retained when the instance is released?

No, the data of a preemptible instance cannot be automatically retained when the instance is released. When a preemptible instance is no longer needed, we recommend that you create snapshots to back up your data and environment and then release the instance. You can purchase preemptible instances anytime. For more information, see Create a snapshot of a disk.

When the protection period of a preemptible instance ends, if the spot price exceeds the user-defined maximum hourly price, the preemptible instance enters the To Be Released state. During the 5-minute period in which a preemptible is pending release, if my bid price is higher than the spot price, can the preemptible instance be retained?

The preemptible instance cannot be retained. Before a preemptible instance is released, a notification is sent and the instance enters the To Be Released state. The state cannot be changed and the instance is automatically released after about 5 minutes.

How do I retain the public IP address of a preemptible instance when the instance is released?

When a preemptible instance is released, its public IP address is reclaimed. If you want to retain the IP address, we recommend that you use Elastic IP Address (EIP). For more information, see Elastic IP addresses.

You can convert the public IP address into an EIP. For more information, see Convert the public IP address of an instance in a VPC to an EIP and Convert the system-assigned public IP address of an instance in the classic network into an EIP.

How is a preemptible instance billed if its lifespan is shorter than 1 hour?

If a preemptible instance is released shortly after it is created and its lifespan is shorter than 1 hour, the instance is billed based on its lifespan in seconds. The hourly price of the instance is the spot price that was in effect when the instance was created. The per-second price of the instance is calculated by using the following formula: Per-second price = Hourly price/3600. The fees for a preemptible instance from creation to release are accurate to two decimal places. Accrued costs of less than USD 0.01 for a preemptible instance are not charged.

To what resources are the prices of preemptible instances applicable?

The prices of preemptible instances are applicable to only instance types. You are charged for other resources such as system disks, data disks, and network bandwidth at the same prices as those of pay-as-you-go instances.

Why do preemptible instances of the same instance type and region vary widely in spot prices across different zones?

Price differences are caused by resource stock differences. Each zone corresponds to different data centers. Within each region, data centers for zones may vary in terms of construction conditions, capacity, sales, and deployment policies. Resource inventories for each instance type may also vary across different zones. The spot prices of preemptible instances fluctuate with supply and demand changes and therefore are different across zones.

May the spot price of a preemptible instance exceed the pay-as-you-go price?

No, the spot price of a preemptible instance can be up to but cannot exceed the pay-as-you-go price. You do not need to worry about being charged more for a preemptible instance than for a pay-as-you-go instance with the same configurations.

For the first hour after a preemptible instance is created, am I charged at a price that fluctuates with the spot price?

No, the hourly price of the first instance hour for a preemptible instance is set at the beginning of the hour and remains in effect for the whole hour.

Do I continue to be charged for preemptible instances after they are stopped?

I purchased a preemptible instance at 08:00:00 with a bid of USD 2 per hour and the spot price of the preemptible instance was USD 2 per hour at 8:30:00. Why was the instance billed at USD 1.5 per hour from 08:30:00 to 9:00:00?

The following figure shows the fluctuations of the spot price.

• Fee for the protection period of 8:00:00 to 9:00:00 (the transaction price was USD 1.5 per hour and the usage duration is 60 minutes) = (1.5/3,600) × 60 × 60 = USD 1.5.
• Fee for the period from 9:00:00 to 9:30:00 (the spot price is USD 0.5 per hour and the usage duration is 30 minutes) = (0.5/3,600) × 30 × 60 = USD 0.25.
• Fee for the period from 9:30:00 to 10:00:00 (the spot price is USD 1 per hour and the usage duration is 30 minutes) = (1/3,600) × 30 × 60 = USD 0.5.

From 8:30:00 to 9:00:00, the preemptible instance was in its protection period and billed based on the spot price at the time of purchase, which was USD 1.5 per hour. After the protection period ends, the instance is billed based on the real-time spot price.

After an preemptible instance enters the To Be Released state, does billing continue?

After an preemptible instance enters the To Be Released state, it is automatically released in 5 minutes. During this 5-minute period, the instance continues to run and be billed. Billing stops only when the instance is released.

Which is more cost-effective: a preemptible instance with a protection period or a preemptible instance without a protection period?

Preemptible instances without a protection period are more cost-effective and have a discount of about 10% off compared with preemptible instances with a protection period.

Is the release rate of preemptible instances without a protection period higher than that of preemptible instances with a protection period?

You can check the release rate of each instance type on the instance buy page in the ECS console regardless of whether you attempt to create preemptible instances with or without a protection period. For each instance type, the release rate is determined by the bidding policy and the supply-demand relationships of resources.

Are preemptible instances without a protection period prioritized for release over those with a protection period?

No, preemptible instances without a protection period are not prioritized for release over those with a protection period.

If I have created a preemptible instance without a protection period, do subsequently created preemptible instances also not have a protection period?

If a preemptible instance does not have a protection period, do I still receive a notification 5 minutes in advance before the instance is released?

Yes, you still receive a notification 5 minutes in advance before a preemptible instance is released even if it does not have a protection period.

Are fewer resources provided for preemptible instances with a protection period than for those without a protection period?

No, the same number of resources are provided for preemptible instances with and without a protection period.

Can I convert between preemptible instances with and without a protection period?

No, you cannot convert between preemptible instances with and without a protection period. By default, each preemptible instance is created with a protection period of 1 hour. You can configure a protection period for preemptible instances only when you create them. The protection period settings of preemptible instances cannot be changed after the instances are created.

What are reserved instances?

A reserved instance is a discount coupon that can be automatically applied to one or more pay-as-you-go instances (excluding preemptible instances) to offer billing discounts. Reserved instances can also be used to reserve instance resources. A combination of reserved instances and pay-as-you-go instances provides higher cost-effectiveness and a higher degree of flexibility as compared with subscription instances.

Do reserved instances provide reserved resources?

Zonal reserved instances provide reserved resources, but regional reserved instances do not.

What operating systems do reserved instances support?

Reserved instances support Windows and Linux. For example, you can purchase a reserved Linux instance and then apply this reserved instance to pay-as-you-go Linux instances that match the attributes of the reserved instance regardless of the image type, such as public images, custom images, shared images, or Alibaba Cloud Marketplace images.

To apply a reserved instance to pay-as-you-go instances created from Bring Your Own License (BYOL) images, submit a ticket.

Which instance families do reserved instances support?

Can reserved instances be applied to preemptible instances?

No, reserved instances cannot be applied to preemptible instances.

Can the instance families of reserved instances be changed?

No, the instance families of reserved instances cannot be changed.

To what scenarios are zonal reserved instances applicable?

We recommend that you purchase zonal reserved instances when you have clear requirements to reserve resources.

To what scenarios are regional reserved instances applicable?

We recommend that you purchase regional reserved instances if you want to have a higher degree of zone flexibility or instance size flexibility.

How is the zone flexibility of reserved instances applied?

Only regional reserved instances provide zone flexibility. Example:

Assume that you are running the following pay-as-you-go instance:

One ecs.c5.xlarge Linux instance in Qingdao Zone B. This instance is named C5PAYG-b.

Assume that you have purchased the following reserved instance:

One regional ecs.c5.xlarge reserved instance in the China (Qingdao) region. This instance is named C5RI.

C5RI is matched to C5PAYG-b.

You release C5PAYG-b and create another pay-as-you-go Linux instance of the same instance type named C5PAYG-c in Qingdao Zone C. C5RI is matched to C5PAYG-c.

How is the instance size flexibility of reserved instances applied?

Only regional reserved instances provide instance size flexibility. Example:

Assume that you have one regional ecs.g5.4xlarge reserved instance. It can be applied to one ecs.g5.4xlarge pay-as-you-go instance, two ecs.g5.2xlarge pay-as-you-go instances, or four ecs.g5.xlarge pay-as-you-go instances.

Assume that you have a one-year regional ecs.g5.xlarge reserved instance. It can be applied to offset the hourly bills of an ecs.g5.xlarge pay-as-you-go instance or 50% of the hourly bills of an ecs.g5.2xlarge pay-as-you-go instance for one year.

Do zonal reserved instances provide instance size flexibility?

No, zonal reserved instances do not provide instance size flexibility. A zonal reserved instance can be applied only to pay-as-you-go instances of the same instance type.

Do zonal reserved instances provide zone flexibility?

No, zonal reserved instances do not provide zone flexibility. A zonal reserved instance can be applied only to pay-as-you-go instances in the same zone as it.

Can a zonal reserved instance be changed into a regional one?

Yes, a zonal reserved instance can be changed into a regional one. The scope of a reserved instance can be changed in the following ways:

• From a zone to a region
• From a region to a zone
• From one zone to another within the same region for a zonal reserved instance

Can the scope of a reserved instance be changed from one region to another?

No, the scope of a reserved instance cannot be changed from one region to another. For example, assume that you have a zonal reserved instance scoped to Hangzhou Zone B. You can change the instance scope to another zone within the China (Hangzhou) region or change the instance into a regional reserved instance scoped to the China (Hangzhou) region. However, you cannot change the scope of the instance to a zone of another region or change the instance into a regional reserved instance scoped to another region.

Can reserved instances be used across accounts?

No, reserved instances cannot be used across accounts.

Can reserved instances be used to cover the storage and network usage charges of pay-as-you-go instances?

No, reserved instances cannot be used to cover the storage or network usage charges of pay-as-you-go instances. Reserved instances are applied to cover the charges for vCPUs and memory of pay-as-you-go instances. Windows reserved instances can also cover image charges.

Can I configure a reserved instance to be applied to a specific pay-as-you-go instance?

No, you cannot configure a reserved instance to be applied to a specific pay-as-you-go instance. When multiple pay-as-you-go instances match the attributes of a reserved instance, the reserved instance is applied based on the optimized matching scheme.

How are reserved instances billed?

Reserved instances are billed separately and support the All Upfront, Partial Upfront, and No Upfront payment options.

The term of a reserved instance begins at the time when the instance is purchased. You are charged based on the payment option that you selected regardless of whether the reserved instance is matched to pay-as-you-go instances. The All Upfront option is most cost-effective.

When does a reserved instance take effect after it is purchased?

After I modify, split, or merge a reserved instance, when does the operation take effect?

When reserved instances are modified, split, or merged, new reserved instances are generated and the original ones become invalid. The new reserved instances take effect and the original ones become invalid. Both occur on the hours of the modification, splitting, or merging operations. For example, assume that you split one ecs.g5.2xlarge zonal reserved instance RI1 into two zonal ecs.g5.xlarge reserved instances RI2 and RI3 at 13:45:00 on February 26, 2019. At 13:00:00 on February 26, 2019, RI1 becomes invalid and RI2 and RI3 take effect. Starting from 13:00:00 on February 26, 2019, the instance type eligible for resource reservation and billing discounts is ecs.g5.xlarge, not ecs.g5.2xlarge anymore. If RI2 and RI3 are matched to pay-as-you-go instances immediately after they take effect, RI2 and RI3 are also applied to offset the hourly bills of ecs.g5.xlarge pay-as-you-go instances starting from 13:00:00 on February 26, 2019.

Why is the No Upfront payment option not displayed on the buy page?

The availability of this option depends on your ECS usage.

Can the payment option of a reserved instance be changed?

No, the payment options of reserved instances cannot be changed.

Can reserved instances be resold?

No, reserved instances cannot be resold.

Can I use Windows reserved instances to cover the image fees of pay-as-you-go Windows instances?

Yes, Windows reserved instances can be applied to cover the image fees of pay-as-you-go Windows instances. This is because Windows reserved instances already include Windows images at no additional cost.

Can Linux reserved instances be applied to cover the image fees of pay-as-you-go Linux instances?

No, Linux reserved instances cannot be applied to cover the image fees of pay-as-you-go Linux instances.

Are the consumption details of reserved instances refreshed every hour?

Yes, the consumption details of reserved instances are refreshed every hour.

Can a reserved instance be applied to more than one pay-as-you-go instance at the same time?

When I attempted to connect to a Linux instance by using Workbench, the connection failed and I received a timeout prompt. Why?

When I attempted to connect to a Linux instance by using Workbench, the connection failed and I was prompted that the connection was denied. Why?

When I attempted to connect to a Linux instance by using Workbench, the connection failed and I was prompted with a username or password error. Why?

When I attempted to connect to a Windows instance by using Workbench, the connection failed and I received a timeout prompt. Why?

When I attempted to connect to a Windows instance by using Workbench, the connection failed and I was prompted with a username or password error. Why?

When I attempted to connect to a Windows instance, the error code 0x112f was returned. Why?

If the 0x112f error code is returned, the Windows instance may have insufficient memory. For information about how to resolve this issue, see What do I do if the error code 0x112f was returned when I attempted to connect to a Windows instance over RDP?

Does a VNC management terminal allow multiple users to log on simultaneously?

No, a VNC management terminal allows a single user to log on at a time.

What do I do if I forget the connection password?

You can reset your connection password. For more information, see Change the VNC password.

Why am I unable to connect to a VNC management terminal even after I reset my connection password?

When I attempted to connect to a VNC management terminal, I was prompted with an authentication failure. What do I do?

What do I do if a black screen appears while I am connected to a VNC management terminal?

What do I do if a VNC management terminal cannot be accessed?

You can use a browser to access the VNC management terminal for troubleshooting. For example, you can use Google Chrome to access the VNC management terminal and press the F12 key to open the developer tools panel. Then, click the Console tab and identify errors based on the information displayed.

Why am I unable to use Internet Explorer 8.0 to access a VNC management terminal?

VNC management terminals support Internet Explorer 10 and later.

We recommend that you use Google Chrome because it is most compatible with the Alibaba Cloud Management Console.

When I use Firefox to access a VNC management terminal, an error message is returned indicating that a secure connection cannot be established. What do I do?

This problem occurs if the encryption algorithm used by your version of Firefox is different from that used by the VNC management terminal.

We recommend that you use Google Chrome because it is most compatible with the Alibaba Cloud Management Console.

How do I connect to a Linux instance?

What are the default username and password used to connect to the operating system of an ECS instance?

How do I adjust the desktop resolution of a Windows instance?

Why do two cursors appear after I log on to a Windows instance by using a VNC management terminal?

What do I do if a Data Plane Development Kit (DPDK) application cannot be deployed on an ECS instance?

We recommend that you deploy DPDK applications on g5ne instances. For more information about the g5ne instance types, see Overview of instance families.

EAL: eal_parse_sysfs_value(): cannot open sysfs value /sys/bus/pci/devices/0000:00:06.0/uio/uio0/portio/port0/start

Can I upgrade the instance types and other configurations of subscription instances?

Yes, you can upgrade the instance types and other configurations of subscription instances. For more information, see Upgrade the instance types of subscription instances.

Can I upgrade the instance types and other configurations of pay-as-you-go instances?

Yes, but you must stop pay-as-you-go instances before you can upgrade their instance types and other configurations. You can upgrade the instance types and other configurations of pay-as-you-go instances by following the instructions in Change the instance type of a pay-as-you-go instance or by calling the ModifyInstanceSpec operation.

How long does it take to upgrade the configurations of an instance?

• Subscription instances do not need to be stopped for their instance types to be upgraded. It takes about 15 minutes to upgrade the instance type of a subscription instance.
• Pay-as-you-go instances must be stopped for their instance types to be upgraded. It also takes about 15 minutes to upgrade the instance type of a pay-as-you-go instance.
• You can upgrade the bandwidths of instances without stopping the instances. The upgrade process takes about 5 minutes.

How is the fee for an instance configuration upgrade calculated?

The fee and the fee calculation method are displayed in the ECS console when you upgrade the instance type or other configurations of an instance. You can also go to the Account Overview page in the Billing Management console to view the fee.

Are my cloud service configurations affected if I upgrade the configurations of ECS instances?

Pay-as-you-go instances must be stopped before their configurations can be upgraded. After you upgrade the configurations of a subscription instance, you must restart the instance for the new configurations to take effect. The upgrade operation interrupts the services that run on the instance for a short period of time. We recommend that you upgrade the configurations of instances during off-peak hours. Instances can seamlessly resume services after upgrades without the need to reconfigure environments.

How do I upgrade ECS resources?

I have upgraded the configurations of an instance but no changes have taken effect. Why?

After you upgrade the configurations of an instance, you must restart the instance by using the ECS console or by calling an API operation for the new configurations to take effect.

After I place an order to upgrade the configurations of an instance, can I cancel the order to restore the instance to its original configurations?

No, after an order to upgrade the configurations of an instance takes effect, the order cannot be canceled and the configurations of the instance are upgraded. If you want to restore the instance to its original configurations, you can downgrade its configurations. You are charged for the configuration downgrade.

What do I do if I cannot access a website that runs on an ECS instance?

This issue may occur due to various causes. Resolve the issue based on the causes. For more information, see What do I do if I cannot access a website hosted on an instance?

My ECS instance was stuck in the Starting state, and AliyunService was disabled or deleted. What do I do?

Problem description: After an ECS instance was started, it remained in the Starting state for an extended period of time and then automatically stopped. You logged on to the instance and found that AliyunService was deleted or disabled in the system services.

How do I use FTP tools in macOS to upload files?

Method 1: Use the Terminal of macOS to upload files

Open the Terminal in macOS or iTerm2 for macOS. To download iTerm2, visit the iTerm2 website. Make sure that you select the correct destination path.

1. Connect to the FTP server.
2. Access the destination directory. In Windows, use the working directory as the destination directory. In Linux, switch to the htdocs directory.
3. Run the put command to upload files.

Method 2: Use a third-party tool to upload files

1. Download Yummy FTP.
2. Install Yummy FTP.
3. Enter the server IP address, username, and password. Set Protocol to Standard (FTP). Set Port to 21 or a different port number that you are using, and leave the SSH key field unselected.
4. Click Connect.
5. In the right-side pane, select the destination directory. In Windows, use the current working directory. In Linux, select the htdocs directory. In the left-side pane, select files. Then, click the Upload icon to upload the files.
   If you attempt to install Yummy FTP and are prompted with a message similar to "Your security preferences only allow the installation of applications from the Mac App Store and authorized developers", perform the following steps:

   1. Choose System Preference > Security and Privacy.
   2. Click the security lock in the lower-left corner of the window and enter the password of the administrator.
   3. Set Allow apps download from to Anywhere.

   Then, you can use Yummy FTP to upload files.

If the problem persists, submit a ticket.

How do I apply for an ICP filing for my domain name after I purchase an ECS instance?

Before you apply for an ICP filing, make sure that your ECS instance meets the ICP filing requirements. For more information, see Prepare and check the instance and access information.

An ECS instance cannot load the kernel to start. What do I do?

Problem description: The system does not respond when you select an option from the GRUB menu on system startup. After you have mounted the LiveCD image to the ECS instance, you can log on to the instance and confirm that the file system permissions are correct and that message logs show no exceptions.

Cause: The system has been attacked by ransomware.

Solution: Back up your data and re-initialize the system.

How do I change the logon password from within an instance?

For information about how to change the logon password from within an instance, see Change the logon password of an instance by connecting to the instance.

Why am I unable to add sound or video cards to ECS instances?

Alibaba Cloud ECS instances are not multimedia servers and do not provide sound or video card components. Sound or video cards cannot be added to ECS instances.

Can I transfer the unused time of an ECS instance to another ECS instance?

No, the unused time of an ECS instance cannot be transferred to other ECS instances. If you want both high flexibility and cost-effectiveness, we recommend that you use a combination of reserved instances and pay-as-you-go instances. For more information, see Overview.

Do ECS instances provide databases by default?

Can I build a database on an ECS instance?

Yes, you can install database software and configure a database environment on an ECS instance. You can also separately purchase ApsaraDB RDS instances in the ApsaraDB RDS console.

Do ECS instances support Oracle databases?

Yes, ECS instances support Oracle databases. Before you install an Oracle database, we recommend that you perform a performance stress test on the ECS instance to ensure that the instance can satisfy the read and write requirements of the database.

Are public and private IP addresses independent? Can I specify or add IP addresses?

In the classic network, public and private IP addresses are independent of each other. Private IP addresses in the classic network are used for communication between ECS instances and between ECS instances and OSS buckets or ApsaraDB RDS instances. If the public bandwidth of an ECS instance is 0 Mbit/s, no public IP address is assigned to the instance. In normal cases, public and private IP addresses in the classic network do not change. You cannot specify, select, or add IP addresses in the classic network.

In virtual private clouds (VPCs), NAT gateways map public IP addresses to private IP addresses. You can add IP addresses by specifying or automatically assigning secondary private IP addresses to elastic network interfaces (ENIs).

Can load balancing be implemented for a single ECS instance?

Both Linux and Windows ECS instances can be load-balanced. Make sure that the configurations of ECS instances used as web servers meet the requirements for website code to run. Load balancing can be implemented for as few as one ECS instance. However, we recommend you implement load balancing for two or more ECS instances within an account.

Can I change the region of an ECS instance that I purchased?

No, the regions of purchased ECS instances cannot be changed. To change the region of an ECS instance, you can use the public template provided by Operation Orchestration Service (OOS)Operation Orchestration Service (OOS) to copy the instance to another region. The new and original instances have identical disk data but different IP addresses.

Can I adjust the partition size of a purchased disk?

For system security and stability purposes, system disks cannot be repartitioned on Windows or Linux instances. If you use a third-party tool to repartition system disks, unknown exceptions such as system failures and data loss may occur.

If you repartition a data disk, data may be lost. We recommend that you do not repartition data disks.

How do I replace the automatically assigned public IP address of an ECS instance with an EIP?

To replace the automatically assigned public IP address of an ECS instance with an EIP, make sure that the instance uses the pay-by-bandwidth billing method for network usage and that you have purchased an EIP. Then, use one of the following methods to replace the public IP address with the EIP:

• Method 1
  1. Change the billing method for network usage from pay-by-bandwidth to pay-by-traffic. For more information, see Public bandwidth.
  2. Convert the automatically assigned public IP address into an EIP. For more information, see Convert the static public IP address of an ECS instance in a VPC to an EIP.
  3. Disassociate the EIP obtained in the previous step. For more information, see Disassociate an EIP from a cloud resource.
  4. Associate the EIP that you purchased with the ECS instance. For more information, see Associate an EIP with an ECS instance.
• Method 2:

  In the OOS console, use the ACS-ECS-ConvertsPublicIPToNewEIPByInstanceId template to replace the automatically assigned public IP address of the ECS instance with an EIP. To perform this operation in the China (Hangzhou) region, access the ACS-ECS-ConvertsPublicIPToNewEIPByInstanceId template in the OOS console and select China (Hangzhou) from the drop-down region list in the top navigation bar.

How do I view subscription ECS instances in all regions within my account?

When can I force stop an ECS instance? What are the consequences?

If an instance cannot be stopped by a proper shutdown procedure, you can force stop the instance. A forced stop is equivalent to disconnecting the power from the instance and can result in loss of unsaved data.

Why am I unable to reactivate my ECS instance?

Why has an ECS instance with release protection enabled been automatically released from a scaling group?

Auto Scaling can automatically release an ECS instance created by a scale-out event even if you have enabled release protection for the instance by using the ECS console or by calling the ModifyInstanceAttribute operation.

To prevent the ECS instance from being automatically released, you must change its state to Protected in the Auto Scaling console. For more information, see Put an ECS instance into the Protected state.

How do I test the packet forwarding rate of an instance?

For information about how to test the packet forwarding rate of an instance, see Best practices for testing network performance. For information about how to test the packet forwarding rate of a g7, c7, or r7 instance, see Use Pktgen to test the network performance of ECS instances.

How do I migrate data between ECS instances?

For more information, see Use the snapshot and image features to migrate instance data.

In addition, Server Migration Center (SMC) also supports the full migration, incremental migration, batch migration, and VPC-based migration features and allows you to migrate data between ECS instances in the SMC console. For more information, see Migrate servers between ECS instances.

What is the AliVulfix process in an ECS instance?

The AliVulfix process is a program that is provided by Alibaba Cloud Security Center. The program scans ECS instances for vulnerabilities.

How do I protect ECS instances against attacks?

ECS instances use Alibaba Cloud Security Center to defend against DDoS attacks. CloudMonitor deployed on ECS instances can automatically detect network attacks and scrub suspicious traffic. Alibaba Cloud performs blackhole filtering to protect ECS instances against high-volume attacks. To strengthen the security of ECS instances, we recommend that you install security software and disable ports that are infrequently used.

What security services does Alibaba Cloud provide?

Alibaba Cloud Security Center is backed by the robust data analysis capabilities of the cloud computing platform of Alibaba Cloud and provides a comprehensive set of security services, such as security vulnerability detection, website trojan detection, host intrusion detection, and anti-DDoS protection.

For information about more security services, visit the Alibaba Cloud Security Services page.

How do I check for mining programs on a server?

You can use one of the following methods to check for mining programs on your server. For more information, see Characteristics of mining programs.

• Check whether the CPU of your server works as expected.
  Note If the CPU utilization of your server significantly increases (for example, to 80% or higher) and an unknown process continuously transmits packets, it indicates that a mining program is running on your server.
• Go to the Alerts page in the Security Center console and check for unhandled alerts of mining programs. If mining programs run on your ECS instance, alerts are generated and need to be handled.

For more information, see Defend against mining programs and Best practices for handling mining programs.

How do I handle mining programs or apply to unlock affected servers?

Handle mining programs

You can handle mining programs or apply to unlock affected servers in the Security Center console or handle mining worms in the Cloud Firewall console. For more information, see Defend against mining programs and Best practices for handling mining programs.

Unlock servers

If a server is locked due to infection by a mining virus or attack, you can apply to unlock the server. To apply to unlock servers, go to the Penalties page of the Security Center console.

I have already renewed an expired Linux instance but I am still unable to access the website hosted on it. What do I do?

Problem description: A Linux ECS instance is in the Stopped state after it has expired. After you have renewed and started the instance, you still cannot access the website hosted on it.

Problem description: This may be because the website service has not been started.

If the problem persists, submit a ticket.

How do I activate a Windows ECS instance within a VPC?

To activate a Windows ECS instance within a VPC, you must use a specific Key Management Service (KMS) domain name. For more information, see How to use the KMS domain name to activate a Windows instance in a VPC.

How do I query, partition, and format the disks of a Linux instance?

You can run the df -h command to check the capacity and usage of disks, and run the fdisk -l command to view disk information. For information about how to partition and format the disks of Linux instances, see Initialize a data disk whose size does not exceed 2 TiB on a Linux instance.

How do I upload files to a Linux instance?

You can use the FTP service to upload files to a Linux instance.

How do I change the owner and owner group of directories and files on a Linux instance?

If the file or directory permissions are not correctly configured on the web server, a 403 error is reported when you access a website hosted on the instance. Before you adjust a file or directory, you must identify the identity under which the file or directory process is running.

You can run the ps and grep commands to query the identities under which processes are running.

You can run the ls -l command to query the owners and owner groups of files and directories.

To change the owners and groups, run the chown command. For example, you can run the chown -R www.www /alidata/www/phpwind/ command to change the owners and groups of all files and directories under the /alidata/www/phpwind directory to the www account.

How do I update software repositories for Linux instances?

You can use an automatic tool to update software repositories for Linux instances. For more information, see Use scripts to automatically update software repositories in Linux instances.

What limits apply to the transfer and change of public IP addresses of ECS instances?

If the problem persists, submit a ticket.

Can I access amazon.com from my ECS instance?

You can access amazon.com from your ECS instance if the instance can properly connect to the Internet.

Why am I unable to access a website hosted outside Chinese mainland after I log on to my ECS instance?

Websites hosted outside Chinese mainland can be accessed by your ECS instance only when the websites comply with the laws, regulations, and regulatory requirements of the country or region where your instance is located. Make sure that your ECS instance can properly connect to the Internet and that the website complies with the preceding laws, regulations, and regulatory requirements.

I cannot purchase more pay-as-you-go instances. What do I do?

If you have reached the maximum number of pay-as-you-go instances that you can purchase, you cannot purchase more pay-as-you-go instances. For more information, see the "Instance limits" section in Limits. You can log on to the ECS console and click Privileges on the Overview page to view your resource quotas. For more information, see View and increase instance quotas.

How can I view the resource quota?

For more information about how to view the limits and quotas of resources, see Limits.

After a pay-as-you-go instance is stopped manually or due to an overdue payment, am I still charged for it?

Stopped due to an overdue payment: When a payment becomes overdue in your account, your pay-as-you-go instance is automatically stopped and billing for the instance stops. Instances do not always remain in the Stopped state after they are stopped due to overdue payments. For more information, see Pay-as-you-go.

What do I do if an order cannot be placed to change the billing method of an instance from pay-as-you-go to subscription?

If one of the preceding errors is reported, adjust the instance accordingly.

How long after an order is paid does it take to change the billing method of an instance from pay-as-you-go to subscription?

The billing method of your instance is changed after the order is paid. It can take up to 4 seconds to change the billing method of 20 instances. After the change is complete, you can see that the billing method of your instance has been changed to Subscription in the ECS console.

What do I do if the billing method of an instance cannot be changed from pay-as-you-go to subscription?

To resolve this problem, submit a ticket.

When I change the billing method of an instance from pay-as-you-go to subscription, does the billing method for network usage of the instance also change?

No, the billing method for network usage of the instance does not change. Only the billing method of instances and disks can be changed from pay-as-you-go to subscription. For information about how to change the billing method for network usage, see Overview of instance configuration changes.

I have an unpaid order to change the billing method of an instance from pay-as-you-go to subscription. If I upgrade the configurations of the instance, is the order still valid?

An order is created when you change the billing method of your instance from pay-as-you-go to subscription. You must pay for the order to complete the change. If you upgrade the configurations of the instance before the order is paid, the order payment cannot be completed because the instance components are different and the original order no longer matches. If you still want to change the billing method of your instance, you must cancel the unpaid order and place a new order.

What do I do if the billing method of an instance cannot be changed from subscription to pay-as-you-go?

You may be unable to change the billing method of an instance from subscription to pay-as-you-go due to one of the following reasons:

• The instance is in a state that does not support billing method changes. For example, you have an unpaid order for the instance.
• The instance is in the Expired state.
• Billing method changes are not allowed because instance information has been changed. For example, the bandwidth of the instance has been temporarily upgraded.

If one of the preceding errors is reported, adjust the instance accordingly. If the problem persists, submit a ticket.

When I attempt to change the billing method of a disk in an instance, an error message is returned indicating that I have already changed the billing method three times. What does this mean?

Each ECS instance can have its configurations downgraded up to three times. Downgrade operations include downgrades of instance specifications, bandwidth downgrades, and the change of the disk billing method from subscription to pay-as-you-go.

Why am I unable to change a pay-as-you-go instance into a subscription one?

How do I view the expiration time of a subscription instance?

You can log on to the ECS console and go to the Instances page to view the expiration time of your subscription instance in the Billing Method column.

Note If the Billing Method column is not displayed, click the icon in the upper-right corner. In the Column Filters dialog box, select Billing Method and click OK.