Hibernate instances - FPGA as a Service - Alibaba Cloud Documentation Center

From a resource management standpoint, FPGA-accelerated instances are considered as Elastic Compute Service (ECS) instances and are managed in the same way you manage other ECS instances. If you do not need to use an ECS instance for a period of time but still want to retain the instance without performing operations such as configuration upgrade or downgrade on the instance, we recommend that you hibernate the instance. Hibernated instances are not the same as stopped instances. When hibernated instances are waked, they automatically restore their applications to the states the applications were in before hibernation. This allows the instances to resume services in a short time.

Background information

When you hibernate an instance, the operating system of the instance saves data from the memory to the system disk of the instance. The saved data includes the applications that run in the operating system and the usage status of the applications. When you wake the instance, the operating system reads the data saved in the system disk, automatically restores the applications to the status before hibernation, and resumes the running state of the instance. In comparison, when you stop and restart an instance, the operating system restarts the backend services and applications.

Note If the instance fails to be hibernated, the instance is automatically shut down. Data in the memory is not saved to the system disk. When the instance is started again, the operating system of the instance restarts the backend services and applications. The operating system cannot restore the applications to the status before hibernation.

Hibernation has different impacts on the billing of instances that use different billing methods:

Subscription instance: The expiration time and billing of the hibernated instance are not affected.
Pay-as-you-go instance: Whether the billing of the hibernated instance is affected is based on whether you select the No Fees for Hibernated Instances option when you hibernate the instance. The following table describes the billing details of resources.

Table 1. Billing of resources on a hibernated instance
Resource	No Fees for Hibernated Instances	Retain Instance and Continue Charging After Instance Is Hibernated
Computing resource (vCPUs and memory)	Release and stop billing	Retain and continue billing
Disk (system disk and data disk)	Retain and continue billing	Retain and continue billing
Internal IP address	Retain and stop billing	Retain and stop billing
Public IP address	Release and stop billing. After the instance is started, a new public IP address is obtained.	Retain and stop billing
EIP	Retain and continue billing	Retain and continue billing
Bandwidth	Continue billing	Continue billing

Limits

The instance hibernation feature is now available only in the US (Silicon Valley) and Germany (Frankfurt) regions, and will be gradually supported in other regions.
Before you can hibernate an instance, the instance must meet the following requirements:
- The instance hibernation feature is enabled when the instance is created.
  Note The instance hibernation feature cannot be disabled after it is enabled. If you do not enable the instance hibernation feature when you create an instance, you cannot hibernate the instance.
- The hibernation agent is installed on the instance.
You can enable the instance hibernation feature only when you create an ECS instance by using an encrypted custom image. The following image versions are supported:
- Windows Server 2016 or later
- Ubuntu 18 or later
- CentOS 7 or later
If the instance hibernation feature is enabled for an ECS instance when the instance is created, you cannot perform the following operations on the instance:
- Create custom images.
- Create snapshots.
- Change the instance type.
- Change the operating system or system disk.
If the instance hibernation feature is enabled for a preemptible instance, you can select only the No Fees for Hibernated Instances option when you hibernate the instance.
You cannot hibernate ECS instances in scaling groups.

Step 1: Enable the instance hibernation feature

You must enable the instance hibernation feature when you create an ECS instance. Otherwise, you cannot hibernate the instance. When you create the instance, you must use an encrypted image.

Obtain an encrypted custom image.
You can use one of the following methods to obtain an encrypted custom image:
- Prepare an encrypted custom image that meets the hibernation requirements.
- Copy an image and encrypt it at the same time. For more information, see Copy an image.
Note For more information about the limits on images, see Limits.

Create an ECS instance and enable the instance hibernation feature when you create the instance.

For more information, see Create an instance by using the wizard. Take note of the parameters described in the following table.


Parameter	Description	Example
Instance	Instance Type: Select an I/O optimized instance type, except ECS Bare Metal Instance. Memory: Windows: Set the memory size to a value less than 16 GiB. Linux: Set the memory size to a value less than 150 GiB.	ecs.g6e.large
Image	Select the encrypted custom image created in the previous step or an existing encrypted custom image that meets the hibernation requirements. Select Instance Hibernation to enable the instance hibernation feature.	encrypted.windows2016 Select Instance Hibernation.
Disk	System Disk: required. The system disk must meet the following requirements: Category: ultra disk, standard SSD, or enhanced SSD (ESSD). Capacity: The system disk capacity must be sufficient. We recommend that you set the system disk capacity to at least twice the memory size. This is because when the instance hibernation feature is enabled, the system disk reserves some space to store memory data. Therefore, the system disk capacity must be sufficient to ensure normal running of the operating system and applications when the system disk stores the memory data. Encryption: By default, the system disk is encrypted if an encrypted image is used. Data Disk: optional. To create data disks for an instance when you create the instance, you must select the disk categories and specify the sizes and quantity of the disks. You must also determine whether to encrypt the disks.	System Disk: Select Enhanced SSD (ESSD), set Disk Capacity to 60 GiB, select Disk Encryption, and then select Default Service CMK from the drop-down list. Data Disk: Select Enhanced SSD (ESSD), set Disk Capacity to 40 GiB, and do not select Disk Encryption.
Network	Select a virtual private cloud (VPC). Note ECS instances in the classic network do not support the instance hibernation feature.	[Default]vpc-bp1opxu1zkhn00g****

Step 2: Install the hibernation agent

After you enable the instance hibernation feature for the instance, you must install the hibernation agent on the instance before you can hibernate the instance.

Create and run one of the following commands to install the hibernation agent on the instance. For more information, see Use the immediate execution feature.
- Windows instance:
```
acs-plugin-manager.exe --exec --plugin ecs-hibernate-win --params "install"
```
- Linux instance:
```
acs-plugin-manager --exec --plugin ecs-hibernate-linux --params "install"
```
Restart the instance to make the hibernation agent take effect. For more information, see Restart instances.

Step 3: Hibernate the instance

After the instance hibernation feature is enabled for the instance and the hibernation agent is installed on the instance, you can hibernate the instance in the Running state. You are unable to connect to the instance when the instance is hibernated.

Log on to the ECS console.
In the left-side navigation pane, choose Instances & Images > Instances.
In the top navigation bar, select a region.
Find the instance that you want to hibernate and choose More > Instance Status > Stop in the Actions column.
In the Stop Instance dialog box, configure the parameters.
1. Set Stopped By to Hibernate.
2. Set Stop Mode to Retain Instance and Continue Charging After Instance Is Hibernated or No Fees for Hibernated Instances based on the billing method of the instance.
  - You are charged for subscription instances even after the instances are hibernated. Select Retain Instance and Continue Charging After Instance Is Hibernated.
  - For pay-as-you-go instances, you can select Retain Instance and Continue Charging After Instance Is Hibernated or No Fees for Hibernated Instances.
    Note For preemptible instances, select No Fees for Hibernated Instances.
  For more information about the difference between Retain Instance and Continue Charging After Instance Is Hibernated and No Fees for Hibernated Instances, see Billing of resources on a hibernated instance in this topic.
3. Click OK.
  Note The instance is stopped and enters the Stopped state. To start the instance, see Start an instance.

References

You can use Operation Orchestration Service (OOS) to hibernate and wake ECS instances at the scheduled time. This way, the hibernation and wake time of a large number of instances can be managed in an automated manner and the costs can be reduced by using the No Fees for Hibernated Instances feature. For more information, see Start or shut down ECS instances at a scheduled time.