topic Deduplication and OSSV backup in ONTAP Discussions

Deduplication and OSSV backup

cjeff — Thu, 05 Jun 2025 06:48:46 GMT

Hi,

IHAC uses following command to backup the MS SQL Server to local files, then uses OSSV to backup the local files.

EXECUTE master.dbo.xp_create_subdir N'E:\DBABackup\OSSQCN_CONFIG'

EXECUTE master.dbo.xp_create_subdir N'E:\DBABackup\OSSQCN_ADMIN'

EXECUTE master.dbo.xp_create_subdir N'E:\DBABackup\OSSQCN_CONTENT1'

EXECUTE master.dbo.xp_create_subdir N'E:\DBABackup\OSSQCN_CONTENT2'

BACKUP DATABASE [OSSQCN_CONFIG] TO DISK = N'E:\DBABackup\OSSQCN_CONFIG\OSSQCN_CONFIG_backup_201108051345.bak' WITH NOFORMAT, NOINIT, NAME = N'OSSQCN_CONFIG_backup_20110805134519', SKIP, REWIND, NOUNLOAD, STATS = 10

BACKUP DATABASE [OSSQCN_ADMIN] TO DISK = N'E:\DBABackup\OSSQCN_ADMIN\OSSQCN_ADMIN_backup_201108051345.bak' WITH NOFORMAT, NOINIT, NAME = N'OSSQCN_ADMIN_backup_20110805134519', SKIP, REWIND, NOUNLOAD, STATS = 10

BACKUP DATABASE [OSSQCN_CONTENT1] TO DISK = N'E:\DBABackup\OSSQCN_CONTENT1\OSSQCN_CONTENT1_backup_201108051345.bak' WITH NOFORMAT, NOINIT, NAME = N'OSSQCN_CONTENT1_backup_20110805134519', SKIP, REWIND, NOUNLOAD, STATS = 10

BACKUP DATABASE [OSSQCN_CONTENT2] TO DISK = N'E:\DBABackup\OSSQCN_CONTENT2\OSSQCN_CONTENT2_backup_201108051345.bak' WITH NOFORMAT, NOINIT, NAME = N'OSSQCN_CONTENT2_backup_20110805134519', SKIP, REWIND, NOUNLOAD, STATS = 10

After several days backup, we find the dedupe ratio is very low.

Does anybody know how to improve the dedupe ratio? Is it because of the database backup parameters?

Thanks,

Jeff

Deduplication and OSSV backup

ajeffrey — Mon, 08 Aug 2011 15:33:05 GMT

Hi Jeff,

First I would have to ask if this is a database with alot of random write activity? If so then obviously the dedupe ratio will be low due to new data. But I assume that this is not the case since you expect it to be lower.

I have had cases when I was running mbralign on alot of similar vmdk files where I had to manually update the fingerprint database before deduplication could produce the expected results. You could try this and then kick off a dedup run to see if it makes any difference.

Regards,

Jeff

Deduplication and OSSV backup

cjeff — Thu, 18 Aug 2011 16:24:33 GMT

The customer deletes the files on the Winows server, then generates the new SQL backup file, then uses the OSSV to do the backup.

So the old files are deleted on the nearstore (and will be locked in the snapshot), new files be snapvaulted to the nearstore.

How can we dedupe the files in the snapshot with the active file system?

Thanks,

Jeff