This topic answers frequently asked questions (FAQ) about ApsaraDB RDS, including basic concepts, billing and purchasing, and instance management.
Basic concepts
What is a database instance?
A database instance is a database server where you can create one or more databases. In each database, you can create one or more tables.
What are primary and secondary instances?
For instances of High-availability Edition, SQL Server Cluster Edition, the node that your services access is the primary instance. Data from the primary instance is synchronized in real time to another node, which is the secondary instance.
You can only access the primary instance. The secondary instance is for backup only and does not handle service requests. If the primary instance fails, a primary/secondary switchover occurs. The secondary instance becomes the new primary instance, and the former primary instance is rebuilt to become the new secondary instance. This process is seamless to your application, although a transient disconnection may occur during the switchover.
NoteFor MySQL Cluster Edition instances, the nodes are called primary and secondary nodes. The secondary nodes are readable. If the primary node fails, any secondary node can be promoted to the primary node.
For more information about the primary and secondary architecture of each edition, see Overview of ApsaraDB RDS editions.
What is a read-only instance?
A read-only instance lets you elastically scale the read capability of your database system and offload read pressure from the primary instance. If your database has many read requests but few write requests, a single instance might not handle the read workload, which can affect your business. In this situation, you can create one or more read-only instances to handle the high volume of read requests and increase your application's throughput.
For more information, see Introduction to read-only ApsaraDB RDS for MySQL instances.
Billing and purchase
Why do I receive a "permission denied" error when I try to create an ApsaraDB RDS instance?
This error commonly occurs when a RAM user tries to create an ApsaraDB RDS instance. We recommend that you create instances by using your Alibaba Cloud account. If you must use a RAM user, you must grant the
AliyunRDSFullAccesspermission to the RAM user. For more information, see Grant permissions to a RAM user.My instance uses the subscription billing method. Why are there extra charges?
The subscription fee covers only the instance and its storage space. You will incur extra charges if you use read-only instances, enable SQL Explorer, use paid performance monitoring features, or exceed your free quota for backup storage. For more information, see Billable items.
Why doesn't my new instance appear in the instance list after I create it?
This issue may occur for the following reasons:
Incorrect region
The region you are currently viewing may not be the same as the region that you selected for the instance. You can switch regions in the upper-left corner of the console.
Insufficient resources in the zone
Resources in a zone are dynamically allocated. If the zone that you selected has insufficient resources when you place the order, the creation fails. We recommend that you try again in a different zone. If the creation fails, you can view the refund on the Orders page.
On the Orders page, click the Product Orders tab. Filter the orders by Type and select Refund to view the refund orders and their status after a creation failure.
Am I charged for an idle pay-as-you-go instance?
Yes. Because a pay-as-you-go instance continues to reserve compute and storage resources when idle, you are still charged hourly.
Can I switch the billing method between subscription and pay-as-you-go?
Yes, you can. For more information, see Change the billing method from pay-as-you-go to subscription and Change the billing method from subscription to pay-as-you-go.
How are charges calculated if I change the specifications of a subscription instance?
For more information, see Change instance specifications.
What are the impacts if my instance expires or has an overdue payment?
For more information, see Overdue payments.
Is public network traffic free for both pay-as-you-go and subscription instances? Is both outbound and inbound traffic free?
Yes, public network traffic for both pay-as-you-go and subscription instances, including inbound and outbound traffic, is free of charge.
Is there a fee for applying for a public endpoint?
No. Applying for a public endpoint is currently free of charge.
For the same CPU and memory, why do entry-level specifications have higher maximum connections and IOPS than enterprise-level specifications?
This is because entry-level specifications belong to the shared or general-purpose instance family, while enterprise-level specifications belong to the dedicated instance family. In practice, enterprise-level specifications offer greater stability due to dedicated CPU and memory resources. For a detailed comparison, see Instance families.
Instance management
How do I authorize a RAM user to manage ApsaraDB RDS instances?
For more information, see Authorize a RAM user to manage ApsaraDB RDS instances.
How do I change the Virtual Private Cloud (VPC)?
Some ApsaraDB RDS for MySQL instances support directly changing the VPC and vSwitch. For more information, see Change the VPC and vSwitch of an ApsaraDB RDS for MySQL instance.
Instances that use cloud disks and have a minor engine version earlier than 20201031 do not support direct VPC changes. To change the VPC, use one of the following methods:
Upgrade the minor engine version and then follow the instructions in this topic to change the VPC.
If you do not want to upgrade the minor engine version, purchase a new instance in the destination VPC, and then migrate your data to the new instance.
Can I access the secondary instance?
No. You can only access the primary instance. The secondary instance is for backup only and does not handle service requests.
When using a VPC, how many private IP addresses does an ApsaraDB RDS for MySQL instance occupy?
Due to the underlying implementation, the number of private IP addresses an instance occupies varies by instance type. The details are as follows:
ApsaraDB RDS for MySQL 5.5, 5.6, 5.7, or 8.0 on High-availability Edition with a local SSD: 1
ApsaraDB RDS for MySQL 5.7 on Basic Edition with a standard SSD: 1
ApsaraDB RDS for MySQL 8.0 on Basic Edition with a standard SSD: 2
ApsaraDB RDS for MySQL 5.7 or 8.0 on High-availability Edition with cloud disks: 3
How can I temporarily stop an ApsaraDB RDS instance that I am not using?
ApsaraDB RDS instances cannot be stopped. If you do not need to use an instance temporarily, migrate its data to a local database and then release the instance. For more information, see Release or unsubscribe from an instance.
Specification changes
What should I do if my instance is locked due to insufficient storage space?
For more information, see What do I do if my ApsaraDB RDS instance is in the 'Locked' state?
What should I do if the instance disk is full?
Enable automatic storage expansion. This feature automatically expands the disk space when it runs low, preventing the instance from being locked. For more information, see Enable automatic storage expansion for an ApsaraDB RDS for MySQL instance and Enable automatic storage expansion for an ApsaraDB RDS for PostgreSQL instance.
Manually expand the storage space of the instance. For more information, see Change instance specifications.
When I upgrade the specifications of the primary instance, are the specifications of its read-only instances automatically upgraded?
No. You must manually upgrade the read-only instances.
How do I change the storage type among local SSDs, standard SSDs, and ESSDs?
For more information, see Change the storage type from cloud disk to local SSD.
How long does it take to expand the storage space?
The system first checks if the host machine has enough storage space. If it does, the expansion is performed directly and takes a short time. If not, the system migrates the instance data to a host with sufficient storage, which takes longer.
Will changing the specifications affect my online services?
During the upgrade, a transient disconnection of about 30 seconds occurs during the switchover.
Do the instance endpoints change after I change the specifications?
The internal/public endpoint and the read/write splitting endpoint do not change, but their corresponding IP addresses might. We recommend that you use the endpoints in your application.
When I try to expand storage space, I receive an 'insufficient inventory' error. What should I do?
You can migrate the instance to another zone and then try to expand the storage space again. Migrating to another zone does not change the connection endpoint, but the IP address corresponding to the endpoint will change. We recommend that your application is configured to automatically reconnect.
Security
Does the IP address whitelist take effect immediately after being configured?
No. It takes about one minute for the new settings to take effect.
Why are there unfamiliar IP address whitelist groups?
If the extra groups contain internal IP addresses, they are usually generated automatically by other Alibaba Cloud services, such as Data Management Service (DMS) or Database Autonomy Service (DAS), to assist with console functions. They do not affect your data, and no action is required. For example, a whitelist group named hdm_security_ips contains only internal IP addresses.
Are there security risks if I only allow internal network access and do not enable public access?
We recommend that you switch your ApsaraDB RDS instance to the VPC network type. This ensures that only Elastic Compute Service (ECS) instances within the same VPC can access your RDS instance, provided you add their internal IP addresses to the IP address whitelist.
What are the consequences of not updating an expired SSL certificate? Will it affect the instance's operation or data security?
If an SSL certificate expires and is not updated, client applications that use encrypted connections will fail to connect to the instance. However, this does not affect the instance's operation or data security.
Auditing
After I enable SQL Explorer, how can I check the size of the generated logs?
You can view the size of the SQL Explorer logs in the Usage Statistics section on the Basic Information page. The SQL Collection Size indicates the log size. You can click View Details for more information.
Connection
How do I troubleshoot connection failures to an instance?
For more information, see Troubleshoot connection failures to an ApsaraDB RDS instance.
Can an instance in a VPC be accessed from the internet?
Yes. After you apply for a public endpoint and configure an IP address whitelist, an instance in either a VPC or the classic network can be accessed from the internet.
Does a primary/secondary switchover affect the connection endpoint?
A primary/secondary switchover does not change the connection endpoint. Only the underlying IP address changes, which does not affect your application.
Accounts and databases
Can I manage accounts with more granular control, such as by source IP address or table access?
Yes. After you connect to the database, you can use commands to grant permissions with more granular control.
What are the specific permissions of privileged accounts and standard accounts?
For more information, see Account privilege list.
Does ApsaraDB RDS provide a root account or super privileges?
No. ApsaraDB RDS does not provide a root account or any account with super privileges. This is a security measure to prevent irreversible data loss or leaks caused by accidental operations.
Can an account created on the primary instance be used on a read-only instance?
Yes. Accounts created on the primary instance are synchronized to its read-only instances. However, you cannot manage accounts on read-only instances. These accounts have only read permissions on the read-only instances and cannot perform write operations.
Read-only instances and read/write splitting
If I set the read weight of a read-only instance to 0, can it still be accessed?
Yes, but not through the read/write splitting endpoint. You can only access it by using the instance's own internal or public endpoint. This setup is typically used to dedicate a read-only instance to a specific service.
Will releasing a read-only instance affect my services?
Yes. Before you release a read-only instance, we recommend that you first set its read weight to 0. Cached connections might still be routed to the instance. New connections are required to route requests to other read-only instances.
What should I do if I encounter issues with read/write splitting?
For more information, see FAQ about read/write splitting.
If the write frequency on my primary instance is low, can I also route read requests to it?
Yes. When you configure the read weight, you can assign a weight to the primary instance as well.
Backup and recovery
Can I disable data backup for an ApsaraDB RDS for MySQL instance?
No. You can reduce the backup frequency to a minimum of twice a week. The minimum retention period for data backups is seven days.
Can I disable log backup for an ApsaraDB RDS for MySQL instance?
Yes, except for instances of Basic Edition. You can disable it by turning off the log backup switch in the backup settings.
Why do backup tasks sometimes fail?
Executing Data Definition Language (DDL) statements during a backup can cause table locks, which may lead to backup failure.
In the log backups, why are there two binlog files with the same name?
Instances of High-availability Edition use a primary-secondary architecture, and both the primary and secondary instances generate binlog files. You can distinguish them by the instance ID. On the Service Availability page, you can find the IDs of the primary and secondary instances. The Primary Instance No. and Secondary Instance No. correspond to the IDs of the primary and secondary instances, respectively.
What is the purpose of downloaded data and log backups?
You can use these backup files to restore data at any time. For more information, see Restore data from a physical backup file of an ApsaraDB RDS for MySQL instance to a self-managed database or Restore data from a logical backup file of an ApsaraDB RDS for MySQL instance to a self-managed database.
Why is a snapshot large when the actual data size is small (for example, a few GB of data results in a snapshot of tens of GB)?Snapshots back up data at the block level. The system only backs up blocks that contain data, so the snapshot is smaller than the disk. However, if data is written in a scattered way, many blocks may be only partially filled. Because the entire block is included in the snapshot, the total snapshot size can be significantly larger than the actual data size.
How can I quickly query data in a backup file?
For full logical backup files, you can use the backup set query feature of Data Disaster Recovery. This allows you to directly query data in backup sets that are stored in the cloud without restoring the data.