:FAQ

Basic concepts

• What are database instances?

  Each 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 RDS instances and secondary RDS instances?

  If you use RDS Cluster Edition for ApsaraDB RDS for SQL Server or RDS High-availability Edition, your application connects to the primary RDS instance of your database system. In addition, the data of the primary RDS instance is synchronized to the secondary RDS instance in real time.

  You can access only the primary RDS instance. The secondary RDS instance serves as a standby and cannot be accessed. If your database system receives a small number of write requests but a large number of read requests, the primary RDS instance may fail to process read requests at high performance and your workloads may be interrupted.

  Note

  If you use RDS Cluster Edition for ApsaraDB RDS for MySQL, primary node and secondary nodes are provisioned in your database system. Secondary nodes are readable. If the primary node is faulty, you can switch your workloads over to a secondary node.

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

• What are read-only RDS instances?

  Read-only RDS instances are used to increase 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, a single primary RDS instance may be overwhelmed by the 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. This way, you can increase the throughput of your application.

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

Billing and purchase

• When I create an RDS instance, the system prompts that I do not have sufficient permissions. Why?

  This is a common error if you create an RDS instance by using the credentials of a RAM user. We recommend that you create an RDS instance by using an Alibaba Cloud account. If you want to create an RDS instance by using the credentials of a RAM user, you must attach the AliyunRDSFullAccess policy to the RAM user. For more information, see Use RAM for resource authorization.

• Why am I charged additional fees for a subscription RDS instance?

  When you purchase a subscription RDS instance, you are charged only for the instance and the storage capacity that you select. If you create read-only RDS instances, enable the SQL Explorer feature or the performance monitoring feature, or use more storage than what is allowed by the free quota on backup storage, you are charged additional fees. For more information, see Billable items.

• After I submit an order to purchase an RDS instance, the system does not respond and I cannot find the RDS instance that I created. Why?

  The preceding issue may occur due to the following reasons:

  • Incorrect region

    The region is different from the region in which your RDS instance resides. You can select the region in which the RDS instance resides in the top navigation bar.

    

  • Insufficient resources

    Resources in zones are dynamically allocated. After you submit a purchase order, the zone that you selected may fail to provide sufficient resources. As a result, the RDS instance cannot be created. We recommend that you select a different 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 refunded fees.

• Am I charged for my pay-as-you-go RDS instances if I do not use them? Am I charged for my pay-as-you-go RDS instances if I do not use them?

  Yes, you are charged an hourly fee for every pay-as-you-go RDS instance that you create even if you do not use these instances. These instances consume computing resources and storage resources even if you do not use these instances.

• Can I change the billing method between subscription and pay-as-you-go?

  Yes, you can change the billing method of an RDS instance between subscription and pay-as-you-go. For more information, see Change the billing method of an ApsaraDB RDS for MySQL instance from pay-as-you-go to subscription and Change the billing method of an ApsaraDB RDS 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 changes.

• What can happen if a subscription RDS instance expires or the payment is overdue?

  For more information, see Overdue payments.

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

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

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

  No, you do not need to pay when you apply for a public endpoint.

• When an entry-level RDS instance and an enterprise-level RDS instance have the same CPU 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 CPU resources. Therefore, an entry-level RDS instance supports a larger maximum number of connections and delivers higher IOPS than an enterprise-level RDS instance. However, an enterprise-level RDS instance provides a more reliable database service because the dedicated instance family supports the exclusive allocations of CPU and memory resources. For more information about the differences, see Instance families.

Instance management

• 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 VPC of an RDS instance?

  • If an RDS instance supports the changes of the virtual private cloud (VPC) and vSwitch, you can directly change the VPC of the RDS instance. For more information, see Change the VPC and vSwitch.

  • If your RDS instance runs a minor engine version earlier than 20201031 and uses cloud disks, you cannot directly change the VPC of the RDS instance. If you want to change the VPC of the RDS instance, use the following methods:

    • Update the minor engine version of the RDS instance. Then, perform the operations that are described in this topic. For more information, see Update the minor engine version.

    • If you do not want to update the minor engine version of the RDS instance, purchase a new RDS instance that resides in the required VPC. Then, migrate the data of the original RDS instance to the new RDS instance. For more information, see Create an ApsaraDB RDS for MySQL instance and Migrate data between ApsaraDB RDS for MySQL instances.

• Can I access the secondary RDS instance of my database system?

  No, you cannot access the secondary RDS instance. You can access only the primary RDS instance. The secondary RDS instance serves as a standby and cannot be accessed.

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

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

  • MySQL 5.5, MySQL 5.6, MySQL 5.7, or MySQL 8.0 on RDS High-availability Edition with local disks: 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 or MySQL 8.0 on RDS High-availability Edition with cloud disks: 3

• How do I stop an RDS instance that I do not want to use?

  You cannot stop an RDS instance. If you do not want to use an RDS instance, you can migrate the data of the RDS instance to an on-premises database and release the RDS instance. For more information, see Release or unsubscribe from an ApsaraDB RDS for MySQL instance.

Specification changes

• What do I do if an RDS instance is locked due to insufficient storage?

  For more information, see What do I do if my ApsaraDB RDS instance is in the Locking state?

• What do I do if the storage capacity of an RDS instance is exhausted?

  • You can configure automatic storage expansion for the RDS instance. This way, if the available storage of the RDS instance is insufficient, the system automatically expands the storage capacity of the RDS instance to prevent the RDS instance from being locked. For more information, see Configure automatic storage expansion for an ApsaraDB RDS for MySQL instance and Configure automatic storage expansion for an ApsaraDB RDS for PostgreSQL instance.

  • You can manually expand the storage capacity of the RDS instance. For more information, see Change instance specifications.

• After I upgrade the primary RDS instance of my database system, does the system automatically upgrade the read-only RDS instances?

  No, you must manually upgrade the read-only RDS instances.

• How do I change the storage type of an RDS instance between local SSD, standard SSD, and ESSD?

  For more information, see How do I change the storage type of an ApsaraDB RDS instance from standard SSD or ESSD to local SSD?

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

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

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

  No, your online workloads on the RDS instance are not interrupted. However, a 30-second transient connection occurs during the subsequent switchover.

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

  No, the internal, public, and read/write splitting endpoints of the RDS 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 an RDS instance to connect your application to the RDS instance.

• When I expand the storage capacity of an RDS instance, what do I do if an error that indicates insufficient storage resources is reported?

  You can migrate the RDS instance to a different zone and then expand the storage capacity of the RDS instance. For more information, see Migrate an ApsaraDB RDS for MySQL instance across zones. After you migrate the RDS instance to a different zone, the endpoints of the 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 the RDS instance.

Security

• After I configure an IP address whitelist, does the IP address whitelist immediately take effect?

  No, after you configure an IP address whitelist, the IP address whitelist requires approximately 1 minute to take effect.

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

  If the IP address whitelists contain private IP addresses, the IP address whitelists may be created by other Alibaba Cloud services, such as Data Management (DMS) and Database Autonomy Service (DAS). The IP address whitelists do not put your data at risk, and no actions are required.

• If I disable Internet access and enable only internal network access for an RDS instance, is the RDS instance exposed to security risks?

  Yes, the RDS instance is exposed to security risks. We recommend that you change the network type of the RDS instance to VPC. This way, only an Elastic Compute Service (ECS) instance that resides in the same VPC can access the RDS instance after you add the required IP address of the ECS instance to an IP address whitelist of the 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 for an RDS instance, does the RDS instance malfunction or does the data security of the RDS instance deteriorate?

  If you do not update the expired SSL certificate, the RDS instance still runs as expected and no security risks occur. However, your application cannot establish encrypted connections to the RDS instance.

Audit

How do I obtain the size of the SQL log data that is generated by the SQL Explorer feature for an RDS instance?

Connections

• What do I do if I cannot connect to an RDS instance?

  For more information, see What do I do if I cannot connect an ECS instance to an ApsaraDB for RDS instance?

• If my application resides outside the VPC to which an RDS instance belongs, can I connect my application to the RDS instance?

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

• Does a primary/secondary switchover on an RDS instance trigger changes to the endpoints of the RDS instance?

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

Databases and accounts

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

  Yes, you can connect to the RDS instance and use commands to grant permissions to accounts at more fine-grained levels. For more information, see Use a database client or the CLI to connect to an ApsaraDB RDS for MySQL instance.

• What permissions do privileged accounts and standard accounts have?

  For more information, see Create accounts and databases.

• 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 helps prevent data loss and leaks that are caused by accidental operations.

• After I create accounts on the primary RDS instance of my database system, can I manage the accounts on the read-only RDS instances?

  No, although the accounts that are created on the primary RDS instance of your database system are synchronized to the read-only RDS instances, you cannot manage the accounts on the read-only RDS instances. The accounts have only read permissions and do not have write permissions on the read-only RDS instances.

Read-only RDS instances and read/write splitting

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

  No, you must manually upgrade the read-only RDS instances. For more information, see Change instance specifications.

• 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 of the read-only RDS instance. 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 be interrupted?

  Yes, your workloads are affected. 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. The cached connection to the read-only RDS instance remains valid. If you want to forward the read requests over the cached connection to other read-only RDS instances, you must establish new connections.

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

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

• If the primary RDS instance of my database system receives a small number of write requests, can I configure the primary RDS instance to process read requests?

  Yes, you can configure the primary RDS instance to process read requests by specifying a read weight for the primary RDS instance. For more information, see Enable the proxy terminal feature for an ApsaraDB RDS for MySQL instance.

Backup and restoration

• Can I disable the data backup feature for an RDS instance that runs MySQL?

  No, you cannot disable the data backup feature for an RDS instance that runs MySQL. However, you can reduce the data backup frequency to as low as twice a week. The data backup retention period must span at least seven days.

• Can I disable the log backup feature for an RDS instance that runs MySQL?

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

• Why does a backup task fail?

  DDL statements trigger locks on tables. If you execute DDL statements during a backup, the backup task may fail due to table locks.

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

  If you use RDS High-availability Edition, your database system consists of a primary RDS instance and a secondary RDS instance. Both instances generate binary log backup files. Each binary log backup file is identified by an instance ID on the Log Backup tab. You can use the instance IDs to distinguish the binary log backup files that are generated by the primary RDS instance from the binary log backup files 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. parameter and the Secondary Instance No. parameter.

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

  You can use the data backup files and log backup files that you downloaded to restore data at 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 is the size of a snapshot for an RDS instance is large even if the amount of data on the RDS instance is small? When the system takes a snapshot of an RDS instance, the system eliminates empty blocks. This way, the size of the snapshot is smaller than the required disk space. The size of each block is 2 MB. However, if write operations are dispersed, a large number of blocks are not full. For example, 3 MB of data may be written to 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 all 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 amount of data.

• How do I query data from backup files?

  If you have full logical backup files, you can use Database Backup (DBS) to query data from these files. This way, you do not need to restore the data of these files. For more information, see Overview.