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jdeschauwer
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Oracle VSS writer using more memory after each VEEAM backup

Post by jdeschauwer » Nov 19, 2012 10:42 am

When creating VEEAM backups on Oracle 11.2 using Oracle VSS, the oravssw.exe uses more memory everytime it is called upon, up to the point that the guest is running out of memory. Restarting the oravssw.exe service helps for a short time, but after 12hrs it uses 500MB again.

I tested the backup with TSM (which according to the dba uses Component-based Shadow Copies) and there were no problems with memory. According to the dba the recommended way to VSS backup Oracle is Component-based Shadow Copies and not Volume-based Shadow Copies, the way VEEAM works.

Any ideas on this ?

Jurgen

Vitaliy S.
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Re: Oracle VSS writer using more memory after each VEEAM bac

Post by Vitaliy S. » Nov 19, 2012 11:28 am

Hi Jurgen,

Veeam just instructs Oracle VSS writer to be prepared for the database backup, so I'm not sure why the memory usage increases all the time. Could you please tell me if you had a chance to contact Oracle support to verify why Oracle VSS writer consumes more and more memory every time this writer is triggered?

Thanks!

jdeschauwer
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Re: Oracle VSS writer using more memory after each VEEAM bac

Post by jdeschauwer » Nov 19, 2012 12:37 pm

I'm working with the dba on this, but she insists that Oracle will demand to reproduce the problem on a physical server. Apparently there's a difference in the way the Oracle VSS writer is being called since there is no logging in Oracle when using TSM but the following traces are found in the Oracle logs when using VEEAM :

ALTER TABLESPACE SYSTEM BEGIN BACKUP
Completed: ALTER TABLESPACE SYSTEM BEGIN BACKUP
ALTER TABLESPACE SYSAUX BEGIN BACKUP
Completed: ALTER TABLESPACE SYSAUX BEGIN BACKUP
...

ALTER TABLESPACE SYSTEM END BACKUP
Completed: ALTER TABLESPACE SYSTEM END BACKUP
ALTER TABLESPACE SYSAUX END BACKUP
Completed: ALTER TABLESPACE SYSAUX END BACKUP

Vitaliy S.
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Re: Oracle VSS writer using more memory after each VEEAM bac

Post by Vitaliy S. » Nov 19, 2012 12:47 pm

I'm not sure how TSM works, but try triggering Volume-Based Shadow Copies manually to see if this issue confirms or not. If you're able to confirm it, then you should be able to reproduce it on the physical system as well.

jdeschauwer
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Re: Oracle VSS writer using more memory after each VEEAM bac

Post by jdeschauwer » Nov 19, 2012 1:04 pm

From the Oracle® Database Platform Guide :

Component-Based Shadow Copies

The Oracle VSS writer supports component-based shadow copies, which are sets of database files. The recommended technique for backing up an Oracle database with VSS writer is to create shadow copies of components. During a backup, the Oracle VSS writer saves the redo generated during snapshot creation in a metadata document. During a restore operation, the writer automatically extracts the redo from the metadata document and applies it to files restored from a snapshot.

Volume-Based Shadow Copies

The Oracle VSS writer supports volume-based shadow copies, which are snapshots of complete drive or volumes. Oracle Database places the files that it manages in a state suitable to create shadow copies. For example, the datafiles are placed in hot backup mode and a new snapshot control file is created for a database in ARCHIVELOG mode. Oracle VSS writer excludes files such as the current control file and online redo logs from the shadow copies. The writer also returns an error if the snapshot cannot be taken. For example, if a NOARCHIVELOG database is open in read/write mode, then the writer returns an error indicating that the snapshot is not possible.

jdeschauwer
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Re: Oracle VSS writer using more memory after each VEEAM bac

Post by jdeschauwer » Nov 19, 2012 1:05 pm

Was reading the same doc :)

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