This topic provides answers to some frequently asked questions about ApsaraDB RDS.

What is a database instance?

A database instance is a database server on which you can create one or more databases. Each database can contain one or more tables.

What are primary and secondary RDS instances?

In the RDS High-availability, Cluster, or Enterprise Edition, the primary RDS instance of your database system is connected to your application. In addition, the primary RDS instance synchronizes data to the secondary RDS instance in real time.

If the primary RDS instance is normal, the secondary RDS instance serves as a standby and cannot be connected to your application. If the primary RDS instance becomes abnormal, your database system fails over to the secondary RDS instance. In this case, the roles of the primary and secondary RDS instances are switched. During the failover, your database service remains available. However, a transient connection may occur.

For more information about the primary and secondary RDS instances in each RDS edition, see Overview of ApsaraDB RDS editions.

What are read-only RDS instances?

Read-only RDS instances are provided to scale the read capability of your database system. If your database system receives a small number of write requests but a large number of read requests, the primary RDS instance may not be capable of processing these read requests and your workloads may be interrupted. In this case, you can create one or more read-only RDS instances to offload read requests from the primary RDS instance. Read-only RDS instances ensure the stability of your database system and increase the throughput of your application.

For more information, see Overview of read-only ApsaraDB RDS for MySQL instances.

Why am I charged additional fees for my subscription RDS instance?

The fee that you pay when you purchase a subscription RDS instance covers only the instance and the storage capacity. If you create read-only RDS instances, enable the SQL Explorer or performance monitoring feature, or use more storage than that allowed by the free quota for backup storage, you are charged additional fees. For more information, see Pricing, billable items, and billing methods.

After I create an RDS instance, why is the ApsaraDB RDS console not responding and why am I unable to find the RDS instance that I created?

This issue may occur due to the following reasons:

  • The RDS instance that you created does not reside in the selected region.

    In the top navigation bar, select the region where the RDS instance resides. Then, you can find the RDS instance that you created.

    Select a region
  • The selected zone cannot provide the required number of resources.

    Resources in zones are dynamically allocated. After you submit the purchase order, the selected zone may be unable to provide the required number of resources. As a result, the RDS instance cannot be created. In this case, we recommend that you select another zone and try again. If the RDS instance cannot be created, you can go to the Orders page in the Billing Management console to view the refund.

Am I still charged if I do not use my pay-as-you-go RDS instance?

Yes, you are still charged an hourly fee for your pay-as-you-go instance that you are not using. This is because a pay-as-you-go RDS instance consumes computing and storage resources even if it is not used. If you do not intend to use your pay-as-you-go RDS instance for a long period of time, we recommend that you save the required data and then release the instance.

Can I switch between the subscription and pay-as-you-go billing methods?

Yes, you can switch between the subscription and pay-as-you-go billing methods. For more information, see Switch an ApsaraDB RDS for MySQL instance from pay-as-you-go to subscription and Switch an ApsaraDB RDS for MySQL instance from subscription to pay-as-you-go.

How much do I need to pay if I change the specifications of my subscription RDS instance?

For more information, see Specification change fees.

What happens if my subscription RDS instance expires or the payment is overdue?

For more information, see Unlock or rebuild an expired or overdue ApsaraDB RDS instance.

Is the inbound and outbound Internet traffic that is consumed for my pay-as-you-go and subscription RDS instances free of charge?

Yes, all the inbound and outbound Internet traffic that is consumed for your pay-as-you-go and subscription RDS instances are free of charge.

Do I need to pay when I apply for a public endpoint?

No, you are not charged when you apply for a public endpoint.

When an entry-level RDS instance and an enterprise-level RDS instance have the same vCPU and memory specifications, why does the entry-level RDS instance support a larger number of connections and deliver higher IOPS than the enterprise-level RDS instance?

An entry-level RDS instance belongs to the shared or general-purpose instance family, whereas an enterprise-level RDS instance belongs to the dedicated instance family. The shared and general-purpose instance families support the reuse of vCPU resources. This allows an entry-level RDS instance to support a larger maximum number of connections and deliver higher IOPS. However, the dedicated instance family supports the exclusive allocations of vCPU and memory resources. This allows an enterprise-level RDS instance to provide a more reliable database service. For more information, see Overview.

How do I authorize a RAM user to manage my RDS instance?

For more information, see Use RAM to manage ApsaraDB RDS permissions.

How do I change the storage type of my RDS instance among local SSD, standard SSD, and enhanced SSD?

For more information, see How do I migrate an ApsaraDB RDS instance from standard or enhanced SSDs to local SSDs?.

How much time is required to expand the storage capacity of my RDS instance?

The required time varies based on whether the physical host on which your RDS instance resides can provide the required amount of remaining storage capacity for your expansion plan. If the remaining storage capacity is sufficient, you do not need to migrate the data of your RDS instance. In this case, the required time is short. If the remaining storage capacity is insufficient, you must migrate the data of your RDS instance to another qualified physical host before you start the expansion. This process is complicated and time-consuming.

After I upgrade my primary RDS instance, does ApsaraDB RDS automatically upgrade the read-only RDS instances?

No, after you upgrade your primary RDS instance, you must manually upgrade the read-only RDS instances.

When I change the specifications of my RDS instance, are my online workloads interrupted?

No, when you change the specifications of your RDS instance, your online workloads are not interrupted. However, a transient connection of about 30 seconds occurs during the subsequent switchover.

After I change the specifications of my RDS instance, do the endpoints of the instance change?

After you change the specifications of your RDS instance, the internal, public, and read/write splitting endpoints of the instance remain unchanged. However, the IP addresses that are associated with the endpoints may change. For more information, see View and change the internal and public endpoints and port numbers of an ApsaraDB RDS for MySQL instance and Enable the read/write splitting feature in the shared proxy of an ApsaraDB RDS for MySQL instance. We recommend that you use the internal, public, or read/write splitting endpoint of your RDS instance to establish a connection from your application.

How do I change the VPC of my RDS instance?

  • If your RDS instance supports virtual private cloud (VPC) and vSwitch changes, you can directly perform these changes. For more information, see the Switch an ApsaraDB RDS for MySQL instance to a new VPC and a new vSwitch.
  • If your RDS instance supports changes between the classic and VPC network types, perform the following steps:
    1. Change the network type from VPC to classic network.
    2. Change the network type from classic network to VPC. During this process, select the VPC that you need.
  • If your RDS instance does not support changes between the classic and VPC network types, perform the following steps:

    Purchase an RDS instance that resides in the required VPC. Then, migrate the data of your RDS instance to the new RDS instance. For more information, see Migrate data between ApsaraDB RDS instances.

Can I access my secondary RDS instance?

No, you cannot access your secondary RDS instance. You can access only your primary RDS instance. Your secondary RDS instance serves only as a standby and does not provide services.

If my RDS instance resides in a VPC, how many private IP addresses does it have?

The number of private IP addresses that your RDS instance has varies based on the database engine and RDS edition that are used.

  • MySQL 5.5, 5.6, 5.7, and 8.0 on RDS High-availability Edition (with local SSDs): 1
  • MySQL 5.6, 5.7, and 8.0 on RDS Enterprise Edition (with local SSDs): 1
  • MySQL 5.7 on RDS Basic Edition (with standard SSDs): 1
  • MySQL 8.0 on RDS Basic Edition (with standard SSDs): 2
  • MySQL 5.7 and 8.0 on RDS High-availability Edition (with standard or enhanced SSDs): 3
  • MySQL 5.7 and 8.0 on RDS Enterprise Edition (with standard or enhanced SSDs): 1

When I expand the storage capacity of my RDS instance, an error that indicates insufficient storage resources is reported. What do I do?

Migrate your RDS instance to another zone. Then, expand the storage capacity of your RDS instance. For more information, see Migrate an ApsaraDB RDS for MySQL instance across zones in the same region. After you migrate your RDS instance to another zone, the endpoints of your RDS instance remain unchanged. However, the IP addresses that are associated with the endpoints change. Make sure that your application is configured to automatically reconnect to your RDS instance.

After I configure an IP address whitelist for my RDS instance, is the IP address whitelist immediately applied?

No, after you configure an IP address whitelist for your RDS instance, the IP address whitelist requires about 1 minute to be applied.

Why do I find IP address whitelists that I did not create?

If these IP address whitelists contain private IP addresses, these IP address whitelists may be created by other Alibaba Cloud services, such as Data Management (DMS) and Database Autonomy Service (DAS). These IP address whitelists do not put your data at risk.

IP address whitelist generated by HDM

If I disable Internet access and enable only internal network access, is my RDS instance exposed to security risks?

Yes, your RDS instance is exposed to security risks. We recommend that you change the network type of your RDS instance to VPC. In this case, only an ECS instance in the same VPC can access your RDS instance after the required IP address is added to an IP address whitelist of your RDS instance. For more information, see Change the network type of an ApsaraDB RDS for MySQL instance.

If I do not update an expired SSL certificate, does my RDS instance malfunction or data security deteriorate?

If you do not update the expired SSL certificate, your RDS instance still runs as normal and no security risks occur. However, if your application uses encrypted connections to communicate with your RDS instance, your application is disconnected.

How do I obtain the size of SQL logs that are generated by the SQL Explorer feature?

Log on to the ApsaraDB RDS console, find your RDS instance, and then go to the Basic Information page. In the Usage Statistics section of the page, you can view the size of the SQL logs that are generated by the SQL Explorer feature.

Log Size

If my application resides outside the VPC of my RDS instance, can it communicate with my RDS instance?

If the IP address of your application is added to an IP address whitelist of your RDS instance, your application can communicate with your RDS instance over the Internet regardless of whether your application resides in a VPC or the classic network. For more information, see Configure an IP address whitelist for an ApsaraDB RDS for MySQL instance.

Does a primary/secondary switchover trigger changes to the endpoints and port numbers of my RDS instance?

No, a primary/secondary switchover does not trigger changes to the endpoints and port numbers of your RDS instance. Only the IP addresses that are associated with the endpoints change. Your application can still connect to your RDS instance by using the endpoints. For more information about primary/secondary switchovers, see Perform a manual or automatic switchover of services between a primary ApsaraDB RDS for MySQL instance and its secondary instance.

Can I manage accounts on my RDS instance at more fine-grained levels, such as the source IP address and table levels?

Yes, you can log on to your RDS instance and use commands to grant permissions to accounts at more fine-grained levels. For more information, see Connect to an ApsaraDB RDS for MySQL instance.

Which specific permissions do privileged and standard accounts have?

For more information, see Create accounts and databases for an ApsaraDB RDS for MySQL instance.

Does ApsaraDB RDS provide accounts that are equivalent to root or superuser accounts?

No, ApsaraDB RDS does not provide accounts that are equivalent to root or superuser accounts. This allows you to protect your RDS instance from data loss and leaks that are caused by unintentional operations.

After I create accounts on my primary RDS instance, can I manage these accounts on the read-only RDS instances?

No, although the accounts created on your primary RDS instance are synchronized to the read-only RDS instances, you cannot manage the accounts on the read-only RDS instances. The accounts only have the read permissions on the read-only RDS instances.

After I upgrade my primary RDS instance, does ApsaraDB RDS automatically upgrade the read-only RDS instances?

No, after you upgrade your primary RDS instance, you must manually upgrade the read-only RDS instances. For more information, see Change the specifications of an ApsaraDB RDS for MySQL instance.

After I set the read weight of a read-only RDS instance to 0, can I still connect to the read-only RDS instance?

Yes, after you set the read weight of a read-only RDS instance to 0, you can still connect to the read-only RDS instance by using the internal or public endpoint. However, you cannot connect to the read-only RDS instance by using the read/write splitting endpoint. For more information, see View and change the internal and public endpoints and port numbers of an ApsaraDB RDS for MySQL instance. This feature is used to configure a read-only RDS instance to process only specific workloads.

If I release a read-only RDS instance, are my workloads interrupted?

Yes, if you release a read-only RDS instance, your workloads are interrupted. Before you release a read-only RDS instance, we recommend that you set the read weight of the read-only RDS instance to 0. For more information, see Modify the latency threshold and read weights of ApsaraDB RDS for MySQL instances. However, the cached connection with your database system remains valid on the released read-only RDS instance. You must close the connection and establish a new one.

What do I do if read/write splitting becomes abnormal?

For more information, see FAQ on read/write splitting.

If my primary RDS instance processes a small number of write requests, can read requests also be sent to my primary RDS instance?

Yes, the read requests can be also sent to your primary RDS instance. You can specify the read weight of the primary RDS instance. For more information, see Read/write splitting.

Can I disable the data backup feature of my ApsaraDB RDS for MySQL instance?

No, you cannot disable the data backup feature of your ApsaraDB RDS for MySQL instance. However, you can reduce the data backup frequency to at least twice a week. The data backup retention period must span at least seven days.

Can I disable the log backup feature of my ApsaraDB RDS for MySQL instance?

Yes, if your ApsaraDB RDS for MySQL instance does not run the RDS Basic Edition, you can disable the log backup feature in the ApsaraDB RDS console.

Why does a backup fail?

DDL statements trigger locks on tables. If you execute DDL statements during a backup, the backup may fail as a result of the table locks.

Why do I find two log backup files with the same name on the Log Backup tab?

If you are using the RDS High-availability Edition, your database system consists of a primary RDS instance and a secondary RDS instance. Both instances generate log backup files. Each log backup file is identified by an Instance ID on the Log Backup tab. The instance IDs allow you to distinguish the log backup files that are generated by the primary RDS instance from those that are generated by the secondary RDS instance. On the Service Availability page, you can view the IDs of the primary and secondary RDS instances based on the Primary Instance No. and Secondary Instance No. fields.

Service Availability page in the original ApsaraDB RDS console

What can I do with the data and log backup files that I downloaded?

You can use the downloaded data and log backup files to restore data any time. For more information, see Restore the data of an ApsaraDB RDS for MySQL instance from a physical backup file to a self-managed MySQL database and Restore the data of an ApsaraDB RDS for MySQL instance from a logical backup file to a self-managed MySQL instance.

Why does my RDS instance have a small amount of data but the size of the generated snapshot is large?

When ApsaraDB RDS takes a snapshot of your RDS instance, ApsaraDB RDS eliminates empty blocks. This allows the size of the snapshot to be smaller than the required disk space. Each block is 2 MB in size. However, if write operations are dispersed, a large number of blocks are not full. For example, 3 MB of data may be written into two, three, or four blocks. In this case, none of these blocks are full. When ApsaraDB RDS calculates the size of the snapshot, ApsaraDB RDS counts in all of these non-empty blocks to which data is written. As a result, the disk space that is occupied by the snapshot is larger than the actual size of the snapshot.

How do I query data from backup files?

You can use Alibaba Cloud Database Backup to query data from full logical backup files. This relieves the need to restore the data. For more information, see Backup set query overview.