Known issues for Amazon RDS Custom for Oracle

Resizing the root or dbbin volumes isn't supported.

Some RDS APIs can be blocked when a database instance is on an older AMI, for example, an AMI that uses Oracle Linux 7. To resolve this issue, patch your DB instance to the latest AMI using OS patching. For more information, see CEV upgrade options.

Before you perform RDS operations, make sure that your AWS account has enough quota for compute and storage.

If the database is in the creation state, and you actively log in to the database or Amazon EC2 host and run commands, database creation might not complete.

Control file multiplexing isn't currently supported because of a read replica issue. Before you create a read replica, make sure to specify only one file name in the CONTROL_FILES initialization parameter on the source database.

You can't change the database mode from PHYSICAL STANDBY (mounted or read-only) to SNAPSHOT STANDBY (converting to read/write).

If an AWS account is part of an AWS Organization with a service control policy (SCP), and the SCP contains a condition key, an RDS Custom for Oracle DB instance might fail to create with the following error:

You can't create the DB instance because of incompatible resources. 
The IAM instance profile role [AWSRDSCustomInstanceRole1-us-east-1] is missing the following permissions: 
EFFECT [Allow] on ACTION(S) [ssm:DescribeAssociation, ssm:DescribeDocument, ssm:GetConnectionStatus, 
  ssm:GetDeployablePatchSnapshotForInstance, ssmmessages:OpenControlChannel, ssm:GetParameters, 
  ssm:ListInstanceAssociations, ssm:PutConfigurePackageResult, ssmmessages:CreateControlChannel, 
  ssm:GetParameter, ssm:UpdateAssociationStatus, ssm:GetManifest, ssmmessages:CreateDataChannel, 
  ssm:PutInventory, ssm:UpdateInstanceInformation, ssm:DescribeInstanceInformation, 
  ssmmessages:OpenDataChannel, ssm:GetDocument, ssm:ListAssociations, ssm:PutComplianceItems, 
  ssm:UpdateInstanceAssociationStatus] for RESOURCE(S) [], EFFECT [Allow] on ACTION(S) [ec2messages:DeleteMessage, 
  ec2messages:FailMessage, ec2messages:GetEndpoint, ec2messages:AcknowledgeMessage, ec2messages:GetMessages, 
  ec2messages:SendReply] for RESOURCE(S) [], EFFECT [Allow] on ACTION(S) [logs:CreateLogStream, 
  logs:DescribeLogStreams, logs:PutRetentionPolicy, logs:PutLogEvents]

To resolve this issue, create a ticket with Support.

Don't remove database user accounts that begin with the string RDS, such as RDSADMIN and RDS_DATAGUARD. RDS Custom for Oracle uses the RDS account for automation. If you remove this user account, RDS Custom moves the instance to the unsupported configuration state.

You can't change the master username for your RDS Custom for Oracle DB instance using the ModifyDBInstance API.

RDS Custom for Oracle rotates user account credentials on all DB instances. For more information, see Rotating RDS Custom for Oracle credentials for compliance programs. If you use an on-premises primary/standby configuration, credential rotation might affect the following resources:

You must configure the crontab file after scale compute, OS upgrades, and other operations where RDS Custom replaces the root volume. We highly recommend that you keep a backup of crontab.

Note the following guidelines when you configure the listener.ora file:

Comments aren't supported in a server parameter file or initialization parameter file.

You must declare the following initialization parameters in the server parameter file (/rdsdbdata/config/oracle_pfile):

If the preceding parameters aren't declared in /rdsdbdata/config/oracle_pfile, read replica creation and scale compute might fail.

You can't delete the symbolic links for configuration files such as the server parameter file, audit files, listener.ora, tnsnames.ora, or sqlnet.ora. You also can't modify the directory structure for these files. RDS Custom automation expects these files to exist in a specific directory structure.

To create a server parameter file from an initialization parameter file, use the following syntax.

CREATE SPFILE='/rdsdbdata/admin/$ORACLE_SID/pfile/spfile$ORACLE_SID.ora' 
    FROM PFILE='/rdsdbdata/config/oracle_pfile';