RDS for SQL Server Constraints

vCPUs and memory

RDS for SQL Server supports Web, Standard, and Enterprise editions.

• Standard Edition supports only instance classes with vCPUs less than 24 or memory less than 128 GB.
• Web Edition supports only instance classes with vCPUs less than 16 or memory less than 64 GB.

For details about other function differences among different editions, see official documentation.

Storage space

• Cloud SSD: 40 GB to 4,000 GB
• Extreme SSD: 40 GB to 4,000 GB

If you need a larger storage space, submit a service ticket to contact customer service.

IOPS

• Cloud SSD: a maximum of 50,000
• Extreme SSD: a maximum of 128,000

The input/output operations per second (IOPS) supported depends on the I/O performance of Elastic Volume Service (EVS) disks. For details, see the description about ultra-high I/O and extreme SSDs in Disk Types and Performance of Elastic Volume Service Service Overview.

Number of databases

A maximum of 100 (can be increased)

-

Number of database accounts

Unlimited

-

Read replica

A maximum of five read replicas can be created for a DB instance.

For more information, see Managing a Read Replica.

Tags

A maximum of 20 tags can be added for a DB instance.

For more information, see Managing Tags.

Free backup space

RDS provides free backup space of the same size as your purchased storage space.

After you pay for the storage space of your DB instance, you will get a backup space of the same size for free. For more information, see How Is RDS Backup Data Billed?

Retention period of automated backups

The default value is 7 days. The value ranges from 1 to 732 days.

For more information, see Configuring an Intra-Region Backup Policy.

Audit logs

The maximum size of an audit log file is 50 MB. Up to 50 audit log files can be displayed.

For more information, see Log Management.

Instance name

• 4 to 64 characters long
• Must start with a letter. Only letters (case sensitive), digits, hyphens (-), and underscores (_) are allowed.

Database name

• 1 to 64 characters long
• Only letters, digits, hyphens (-), underscores (_), and periods (.) are allowed. It cannot start or end with an RDS for SQL Server system database name. RDS for SQL Server system databases include master, msdb, model, tempdb, resource, rdsdistribution, and rdsadmin.
• Databases cannot be created for a DB instance that is being restored or whose instance class is being changed.
• Databases with HA relationships can be renamed only after the replication relationships are removed.

Account name

• 1 to 128 characters long
• Only letters, digits, hyphens (-), and underscores (_) are allowed. It must be different from system accounts. System accounts include rdsadmin, rdsuser, rdsbackup, and rdsmirror.

Backup name

• 4 to 64 characters long
• Must start with a letter. Only letters (case sensitive), digits, hyphens (-), and underscores (_) are allowed.

Parameter template name

• 1 to 64 characters long
• Only letters (case sensitive), digits, hyphens (-), underscores (_), and periods (.) are allowed.

rdsuser roles

rdsuser password

• 8 to 32 characters long
• Must contain at least three types of the following characters: uppercase letters, lowercase letters, digits, and special characters (~!@#$%^*-_+?,).

For more information, see Resetting the Administrator Password.

Database port

RDS for SQL Server instances can use port 1433 (default) or ports 2100 to 9500 (excluding 5355 and 5985). For RDS for SQL Server 2017 and 2019 Enterprise, Standard, and Web editions, ports 5050, 5353, and 5986 cannot be used, either.

For more information, see Changing a Database Port.

Disk encryption

If you enable disk encryption during instance creation, the disk encryption status and the key cannot be changed later.

For more information, see Performing a Server-Side Encryption.

VPC

The VPC where a DB instance is located cannot be changed after the instance is created.

Security group

• By default, you can create a maximum of 100 security groups in your cloud account.
• By default, you can add up to 50 security group rules to a security group. For more information, see Configuring Security Group Rules.
• One RDS DB instance can be associated with multiple security groups, and one security group can be associated with multiple RDS DB instances.
• When creating a DB instance, you can select multiple security groups. For better network performance, you are advised to select no more than five security groups. For more information, see Changing a Security Group.

System account

To provide O&M services, the system automatically creates system accounts when you create RDS for SQL Server DB instances. These system accounts are unavailable to you.

• rdsadmin: an account that has the sysadmin role and is used to query DB instance information, monitor instance status, rectify faults, migrate data, and restore data.
• rdsmirror: a primary/standby replication account, used to create mirroring endpoints.
• rdsbackup: a backup account, used for backend backup.
• Mike: a Windows system account of RDS for SQL Server. It is used to initialize SQL statements during the DB instance initialization, including creating the rdsadmin database and related accounts.

Instance parameter

To ensure the optimal performance of RDS, you can modify parameters in the parameter template you created as needed.

For more information, see Modifying RDS for SQL Server Instance Parameters.

Instance deployment

ECSs where DB instances are deployed are not directly visible to you. You can only access the DB instances through IP addresses and database ports.

Data migration

You can migrate data from on-premises SQL Server databases or SQL Server databases built on other clouds to RDS for SQL Server, or from an RDS for SQL Server instance to another RDS for SQL Server instance.

Data migration tools include Data Replication Service (DRS) and Data Admin Service (DAS). You are advised to use DRS because it is easy to use and can complete a migration task in minutes. DRS facilitates data transfer between databases, helping you reduce DBA labor costs and hardware costs.

RDS for SQL Server does not support database import to system databases master or msdb.

For more information, see Migration Solutions.

High CPU usage

If the CPU usage is high or close to 100%, data read/write and database access will become slow, and an error will be reported during data deletion.

For details, see High CPU Usage of RDS for SQL Server Instances.

Rebooting a DB instance

DB instances cannot be rebooted through commands. They must be rebooted through the RDS console.

Stopping or starting a DB instance

• You can temporarily stop pay-per-use instances to save money. For more information, see Stopping an Instance.
• After stopping your instance, you can restart it to begin using it again.

Viewing backups

You can download backups for local storage. To download a backup, you can use OBS Browser+ or the download URL.

For more information, see Downloading a Backup File.

Log management

RDS for SQL Server logging is enabled by default and cannot be disabled.

Recycle bin

RDS allows you to move unsubscribed yearly/monthly DB instances and deleted pay-per-use DB instances to the recycle bin. You can rebuild a DB instance that was deleted up to 7 days ago from the recycle bin.

Maximum number of databases

100 (can be increased)

100 (can be increased)

100 (can be increased)

Number of database accounts

Unlimited

Unlimited

Unlimited

Creation of user, LOGIN, or database

Supported

Supported

Supported

Database-level DDL trigger

Supported

Supported

Supported

Database permission authorization

Supported

Supported

Supported

KILL permission

Supported

Supported

Supported

LinkServer

Supported

Supported

Supported

Distributed transaction

Supported

Supported

Supported

SQL Profiler

Supported

Supported

Supported

Tuning Adviser

Supported

Supported

Supported

Change Data Capture (CDC)

Supported

Supported

Supported

Change tracking

Supported

Supported

Supported

Windows domain account login

Supported

Supported

Supported

Email

Supported

Supported

Supported

SQL Server Integration Services (SSIS)

Supported

Supported

Supported

SQL Server Analysis Services (SSAS)

Not supported

Not supported

Not supported

SQL Server Reporting Services (SSRS)

Supported

Supported

Supported

R Services

Not supported

Not supported

Not supported

Common Language Runtime (CLR)

SAFE supported

SAFE supported

SAFE supported

Asynchronous communication

Not supported

Not supported

Not supported

Publications & Subscriptions

Supported

Supported

Supported

Policy management

Not supported

Not supported

Not supported

Private domain name

Supported

Supported

Supported

SQL Agent job

Supported

Supported

Supported