Sep 29

Compressalways and TDP

Domino, TDP Comments Off on Compressalways and TDP
Problem(Abstract)
While performing an Oracle backup using the Data Protection for Oracle or Domino client, the following error was witnessed:
ANS1360I Compressed Data Grew
 
 
Cause
Using compression, if the compressalways parameter is set to no, this should resend the object without compression. Oracle/RMAN is actually doing the backup processing and does not have automatic retry logic build into the application. Thus, when the compressed object grows in size during the backup, this can cause the backup to fail.The TSM Client Manual has the following for Compressalways option.

Syntax: COMPRESSAlways Yes | No

Parameters:

Yes –> File compression continues even if the file grows as a result of compression. This is the default.

No –> Backup-archive client objects are resent uncompressed if they grow during compression. API behavior depends on the application. Application backups may fail.

 

Resolving the problem
The Data Protection for Oracle client is a library interface that uses the TSM API to redirect the data being backed up to the TSM server. The TSM API has the capability to perform software compression on the backup data. If the data that is being compressed actually grows during the compression processing, and Compressalways=no is set in the dsm.opt file, it will generate the following error message and also abort/stop the current backup :ANS1360I Compressed Data Grew
Explanation: The size of the file after compression is greater than the size of the file before compressed.
System Action: Even though the size of the file increased, the file is compressed.When the Compressalways parameter is set to NO, this will cause the storing of the data to be aborted and then resend this data uncompressed. However, for the TSM API, it relies on the application to perform the retry that is needed to resend the data. In the case of the DP for Oracle, it is actually Oracle that is performing the backup processing and thus it would be the responsibility of Oracle to perform any necessary retries. However, the Oracle application does not contain any retry logic and thus the backup fails when the ANS1360I error is encountered.

To resolve the error for the data growing during compression of the data being sent to the TSM Server, do the following

> Disable Compression the DP for Oracle client. This can be set in the dsm.opt file that is being used by the DP client or set on the TSM Server within the Node definition.

OR

> Enable compression and compressalways values to YES|True

NOTE:

Compressalways = Yes as the default from API V3.1 or higher

written by Bosse