This topic provides answers to some commonly 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 used to communicate with your application. In addition, the primary RDS instance synchronizes data to the secondary RDS instance in real time.

If the primary RDS instance is working as normal, the secondary RDS instance serves as a backup and does not provide database services. If the primary RDS instance becomes abnormal, your database system fails over to the secondary RDS instance. In this case, the primary RDS instance is demoted to a secondary RDS instance, and the secondary RDS instance is promoted to the primary RDS instance. During the failover, your database service remains available. However, a transient connection error may occur.

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

What are read-only RDS instances?

Read-only RDS instances are provided to scale the read capability of your database system. If a large number of read requests overwhelm the primary RDS instance, 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 increases the throughput of your application.

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

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

The fee that you pay when you purchase your 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 allowed by the free quota for backup storage, you are subject to 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 your 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 tothe 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 the billing method from pay-as-you-go to subscription and Switch the billing method 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 for 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 of 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 CPU and memory specifications, why does the entry-level RDS instance support a larger number of connections and deliver higher input/output operations per second (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. 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 CPU and memory resources. This allows an enterprise-level RDS instance to provide a more reliable database service. For more information, see Instance families.

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

For more information, see Use RAM to manage ApsaraDB for 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 to change a cloud disk to a local disk.

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

The required time varies based on whether the physical host that contains your RDS instance 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, which means that 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 error of about 30 seconds may occur during the subsequent switchover.

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

After you change the specifications of your RDS instance, the internal, public, and read/write splitting endpoints 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 function 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 VPC and vSwitch changes, you can directly perform these changes. For more information, see Switch to a new VPC and VSwitch for an RDS MySQL instance.
  • 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 want.
  • If your RDS instance does not support changes between the classic and VPC network types, perform the following steps:

    Purchase a new 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 for 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 backup and does not provide services.

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

The number of private IP addresses that your RDS instance occupies varies based on the selected database engine and RDS edition.

  • 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 appears that indicates insufficient storage resources. 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 may 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 whitelists may be created by other Alibaba Cloud services, such as Data Management (DMS) and Database Autonomy Service (DAS). These whitelists do not put your data at risk.

IP address whitelist created 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 the data security deteriorate?

If you do not update the expired SSL certificate, your RDS instance still runs and no security risks occur. However, if you have applications that use encrypted connections to communicate with your RDS instance, the applications are 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 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. This applies regardless of whether your application resides in a VPC or the classic network. For more information, see Control access to 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.

Can I manage accounts on my RDS instance at more granular 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 granular 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 super users?

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

Can I manage the accounts created on my primary RDS instance from 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 have only the read permissions on the read-only RDS instances.

After I upgrade my primary RDS instance, does ApsaraDB RDS automatically upgrade 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 provided for you to configure a read-only RDS instance to process only specific workloads.

If I release a read-only 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 a small number of write requests are sent to the primary RDS instance, can the read requests be sent to the primary RDS instance?

Yes, the read requests can be sent to the primary RDS instance. You can specify the read weights 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 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?

Data definition language (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?

In 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.

Primary Instance No. and Secondary Instance No.

What do 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 Use a physical backup file to restore an ApsaraDB RDS for MySQL instance to a user-created 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 volume 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 greater than the actual size of the snapshot.

How do I query data from backup files?

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