Discovering and analyzing migration limitations with Amazon DMS Fleet Advisor
You can use the DMS data collector to discover database features that your target engine doesn't support. To choose the right migration target, you should consider these limitations.
The DMS data collector discovers specific source database features. Then, DMS Fleet Advisor analyses source features from a migration standpoint to the specified target and provides additional information about the limitation and includes recommended actions to address or avoid this limitation. Also, DMS Fleet Advisor calculates the impact of these limitations.
The list of limitations is available in the Target engine details page. Navigate to this page from the Recommendations page in the left navigation menu. From the list of targets, choose the target engine to examine. The list of limitations is at the bottom of the page.
The following table includes MySQL database features that Amazon RDS for MySQL doesn't support.
Limitation | Description | Impact |
---|---|---|
Authentication plugins |
Amazon RDS doesn't support MySQL authentication plugins. |
Low |
Error logging to the system log |
Amazon RDS doesn't support writing the error log to the system log. |
Low |
Global transaction identifiers |
You can use global transaction identifiers with all RDS for MySQL 5.7 versions, and RDS for MySQL version 8.0.26 and higher MySQL 8.0 versions. |
Low |
Group Replication |
Amazon RDS doesn't support the MySQL Group Replication plugin. |
Low |
InnoDB tablespace encryption |
Amazon RDS doesn't support the InnoDB tablespace encryption. |
Low |
InnoDB reserved word |
InnoDB is a reserved word for Amazon RDS for MySQL. You can't use this name for a MySQL database. |
Low |
Keyring plugin |
Amazon RDS doesn't support the MySQL keyring plugin. |
Low |
Password validation plugin |
Amazon RDS doesn't support the MySQL
|
Low |
Persisted system variables |
Amazon RDS doesn't support MySQL persisted system variables. |
Low |
Restricted access |
Amazon RDS restricts access to certain system procedures and tables that require advanced permissions. Also, Amazon RDS doesn't allow direct host access to a DB instance by using Telnet, Secure Shell (SSH), or Windows Remote Desktop Connection. |
Low |
Rewriter query rewrite plugin |
Amazon RDS doesn't support the MySQL Rewriter query rewrite plugin. |
Low |
Semisynchronous replication |
Amazon RDS doesn't support the MySQL semisynchronous replication. |
Low |
Transportable Tablespaces |
Amazon RDS doesn't support the MySQL Transportable Tablespaces feature. |
Low |
X Plugin |
Amazon RDS doesn't support the MySQL X Plugin. |
Low |
The following table includes Oracle database features that Amazon RDS for Oracle doesn't support.
Limitation | Description | Impact |
---|---|---|
Active Data Guard |
You can't use Active Data Guard with Oracle multitenant container databases (CDB). |
Medium |
Automatic Storage Management |
Amazon RDS doesn't support Oracle Automatic Storage Management (Oracle ASM). |
Medium |
Database Activity Streams |
Amazon RDS doesn't support Oracle Database Activity Streams for the single-tenant architecture. |
High |
File size limit |
The maximum size of a single file on RDS for Oracle DB instances is 16 TiB. |
Medium |
FTP and SFTP |
Amazon RDS doesn't support FTP and SFTP. |
Medium |
Hybrid partitioned tables |
Amazon RDS doesn't support Oracle hybrid partitioned tables. |
High |
Oracle Data Guard |
Amazon RDS doesn't Oracle Data Guard for the single-tenant architecture. |
High |
Oracle Database Vault |
Amazon RDS doesn't support Oracle Database Vault. |
High |
Oracle DBA privileges Vault |
Amazon RDS has limitations for Oracle DBA privileges. For more information, see Limitations for Oracle DBA privileges. |
High |
Oracle Enterprise Manager |
Amazon RDS doesn't Oracle Enterprise Manager for the single-tenant architecture. |
High |
Oracle Enterprise Manager Agent |
Amazon RDS doesn't Oracle Enterprise Manager Agent for the single-tenant architecture. |
Medium |
Oracle Enterprise Manager Cloud Control Management Repository |
You can't use an Amazon RDS for Oracle DB instance for Oracle Enterprise Manager Cloud Control Management Repository. |
High |
Oracle Flashback Database |
Amazon RDS doesn't support the Oracle Flashback Database feature. |
High |
Oracle Label Security |
Amazon RDS doesn't support Oracle Label Security for the single-tenant architecture. You can use Oracle Label Security only with multitenant container databases (Oracle CDB). |
High |
Oracle Messaging Gateway |
Amazon RDS doesn't support Oracle Messaging Gateway. |
High |
Oracle Real Application Clusters |
Amazon RDS doesn't support Oracle Real Application Clusters (Oracle RAC). |
High |
Oracle Real Application Testing |
Amazon RDS doesn't support Oracle Real Application Testing. |
High |
Oracle Snapshot Standby databases |
Amazon RDS doesn't support Oracle Snapshot Standby databases. |
High |
Public synonyms |
Amazon RDS doesn't support public synonyms for Oracle-supplied schemas. |
Medium |
Schemas for unsupported features |
Amazon RDS doesn't support schemas for Oracle features and components that require system privileges. |
High |
Pure unified auditing |
Amazon RDS doesn't support the pure unified auditing. You can use the unified auditing in mixed mode. |
Medium |
Workspace Manager |
Amazon RDS doesn't support the Oracle Database Workspace Manager
|
High |
The following table includes PostgreSQL database features that Amazon RDS for PostgreSQL doesn't support.
Limitation | Description | Impact |
---|---|---|
Concurrent connections |
The maximum number of concurrent connections to your RDS for PostgreSQL
instance is limited by the |
Low |
Newest versions |
Amazon RDS doesn't apply major version upgrades automatically. To perform a major version upgrade, modify your DB instance manually. For more information, see Choosing a major version upgrade for PostgreSQL. |
Low |
Reserved connections |
Amazon RDS reserves up to 3 connections for system maintenance. If you specify a value for the user connections parameter, add 3 to the number of connections that you expect to use. |
Low |
Supported extensions |
RDS for PostgreSQL supports a limited number of extensions for the
PostgreSQL database engine. You can find a list of supported
extensions in the default DB parameter group for your PostgreSQL
version. You can also see the current extensions list using
|
Low |
Tablespace splitting or isolation |
You can't use tablespaces for I/O splitting or isolation. In RDS for PostgreSQL, all storage is on a single logical volume. |
Low |
The following table includes SQL Server database features that Amazon RDS for SQL Server doesn't support.
Limitation | Description | Impact |
---|---|---|
Backing up to Microsoft Azure Blob Storage |
RDS for SQL Server doesn't support backing up to Microsoft Azure Blob Storage. |
Medium |
Buffer pool extension |
RDS for SQL Server doesn't support the buffer pool extension. |
High |
Custom password policies |
RDS for SQL Server doesn't support custom password policies. |
Medium |
Data Quality Services |
RDS for SQL Server doesn't support SQL Server Data Quality Services (DQS). |
High |
Database Log Shipping |
RDS for SQL Server doesn't support database Log Shipping. |
High |
Database names |
Database names have the following limitations: can't start with rdsadmin; can't start or end with a space or a tab; can't contain any of the characters that create a new line; can't contain a single quotation mark ('). |
Medium |
Database snapshots |
RDS for SQL Server doesn't support database snapshots. You can use only DB instance snapshots in Amazon RDS. |
Medium |
Extended stored procedures |
RDS for SQL Server doesn't support extended stored procedures, including
|
High |
File tables |
RDS for SQL Server doesn't support file tables. |
Medium |
FILESTREAM support |
RDS for SQL Server doesn't provide FILESTREAM support. |
Medium |
Linked servers |
RDS for SQL Server provides limited support for linked servers. |
High |
Machine Learning and R Services |
RDS for SQL Server doesn't support Machine Learning and R Services because you need OS access to install these services. |
High |
Maintenance plans |
RDS for SQL Server doesn't support maintenance plans. |
High |
Performance Data Collector |
RDS for SQL Server doesn't support Performance Data Collector. |
High |
Policy-Based Management |
RDS for SQL Server doesn't support Policy-Based Management. |
Medium |
PolyBase |
RDS for SQL Server doesn't support PolyBase. |
High |
Replication |
RDS for SQL Server doesn't support replication. |
Medium |
Resource Governor |
RDS for SQL Server doesn't support Resource Governor. |
High |
Server-level triggers |
RDS for SQL Server doesn't support server-level triggers. |
Medium |
Service Broker endpoints |
RDS for SQL Server doesn't support Service Broker endpoints. |
High |
SSAS |
Consider the limitations that apply to running SQL Server Analysis Services (SSAS) on RDS for SQL Server. For more information, see Limitations. |
Low |
SSIS |
Consider the limitations that apply to running SQL Server Integration Services (SSIS) on RDS for SQL Server. For more information, see Limitations. |
Low |
SSRS |
Consider the limitations that apply to running SQL Server Reporting Services (SSRS) on RDS for SQL Server. For more information, see Limitations. |
Low |
Storage size for SQL Server DB instances |
The maximum storage size for SQL Server General Purpose (SSD) storage and Provisioned IOPS storage instances is 16 TiB. The maximum storage size for SQL Server Magnetic storage instances is 1 TiB. |
High |
Stretch Database |
RDS for SQL Server doesn't support the SQL Server Stretch Database feature. |
Medium |
T-SQL endpoints |
RDS for SQL Server doesn't support all operations that use |
High |
TRUSTWORTHY database property |
RDS for SQL Server doesn't support the |
Medium |
The following table includes a list of recommendation issues. DMS Fleet Advisor analyses source and target database features and provides these migration limitations. The limitation with Blocker impact means that DMS Fleet Advisor can't generate target recommendations for the source database.
Limitation | Description | Impact |
---|---|---|
Appropriate instance is not found |
Amazon DMS can't find a target instance that can work as a right-sized migration destination for a combination of your source database metrics. |
Blocker |
Appropriate instance is not found by IOPS |
The source database uses a number of IOPS, which exceeds the maximum number of IOPS for the possible target DB instances. |
Blocker |
Appropriate instance is not found by RAM |
The source database uses a number of GB of RAM, which exceeds the maximum size of RAM for the possible target DB instances. |
Blocker |
Appropriate instance is not found by storage size |
The source database uses a number of TB of storage, which exceeds the maximum storage size for the possible target DB instances. |
Blocker |
Appropriate instance is not found by edition |
The source database has an edition, which is not supported by Amazon RDS. |
Blocker |
Appropriate instance is not found by CPU cores |
The source database has a number of CPU cores, which exceeds the maximum number of CPU cores for the possible target DB instances. |
Blocker |
Appropriate instance is not found by version |
Your source database has version, which Amazon DMS doesn’t recognize. |
Blocker |
CPU parameter is undefined |
The DMS data collector didn't collect information about the CPU that your source database uses. Make sure that you collected the required metrics and configured credentials for data forwarding in your data collector. See Configuring credentials for data forwarding. |
Blocker |
Memory parameter is undefined |
The DMS data collector didn't collect information about the memory that your source database uses. Make sure that you collected the required metrics and configured credentials for data forwarding in your data collector. See Configuring credentials for data forwarding. |
Blocker |
Storage size parameter is undefined |
The DMS data collector didn't collect information about the storage size that your source database uses. Make sure that you collected the required metrics and configured credentials for data forwarding in your data collector. See Configuring credentials for data forwarding. |
Blocker |
Storage IOPS parameter is undefined |
The DMS data collector didn't collect the storage IOPS metrics for your source database uses. Make sure that you collected the required metrics and configured credentials for data forwarding in your data collector. |
Blocker |
Not Enough Data |
The DMS data collector didn't collect enough data to generate a target recommendation. Make sure that you configured credentials for data forwarding in your data collector. See Configuring credentials for data forwarding. |
Blocker |
Database edition is undefined |
The DMS data collector didn't collect information about your source database edition. Make sure that you collected the required metrics and configured credentials for data forwarding in your data collector. See Configuring credentials for data forwarding. |
Blocker |
Unknown Error |
DMS Fleet Advisor can't generate target recommendations for your source database. |
Blocker |
Database version is undefined |
The DMS Fleet Advisor didn't collect information about your source database version. DMS Fleet Advisor recommends that you use the latest database version for your source database. If you choose this recommendation, then you must upgrade your database version. Review the generated target recommendations for your source database and make sure that these recommendations meet your requirements. |
High |
Increase the number of database connections in RDS settings |
Your source database requires certain number of connections. By
default, the number of available connections for Amazon RDS database
instances is different. Make sure that you change this default value
when you create your RDS database instance. To do so, update the
max_connections parameter value in Parameter
Groups. |
Medium |
Target edition is compatible |
The target recommendation for your source database uses a different database edition. Your source database edition supports the same features as the recommended target edition. However, choosing this new database edition might increase your expenses. |
Medium |
Storage throughput parameter is undefined |
The DMS data collector didn't collect the storage throughput metrics for your source database uses. Review the generated target recommendations for your source database and make sure that these recommendations meet your requirements. |
Medium |
Database connection number parameter is undefined |
The DMS data collector didn't collect information about the number of connections that your source database uses. Review the generated target recommendations for your source database and make sure that these recommendations meet your requirements. Alternatively, request a quota increase. |
Medium |
Database downgrade version |
Your source database runs on a higher version than the Amazon RDS database. To downgrade your database version, make sure that you don't use the features that aren't implemented in lower version. Alternatively, use Amazon EC2 as a migration target. |
Medium |
Target edition is different |
The target recommendation for your source database uses a different database edition. Your source database edition is compatible with the recommended target edition. However, the recommended target database edition doesn't support some features of your source database edition. Choosing this new database edition might increase your expenses. |
Medium |
Upgrade from an unsupported version |
Your source database has reached the end of support stage. To use the
latest DB engine version as a target, upgrade your database before the
migration. Alternatively, use Amazon EC2 as a migration
target. Depending on the database engine, use one of the following links for Learn more: |
Medium |