TSM DRM behaviour with incremental backups
Hi guys
We have a 'forever incremental' backup policy implemented and I have been testing putting in place a DRM process.
It hadn't occurred to me that I might see some odd behaviour with the copy of the primary tape storage pool to the offsite storage pool as part of the DRM process.
My expectation was that as part of this command,
backup stgpool primpool offsitepool wait=yes
ALL data would be copied across from primpool to offsitepool each time it was run.
I have reuse delay set to 7 days and dbb expiry set to 7 days.
On monitoring this, the 1st time it was run I saw ALL data was copied across. However on the 2nd week, only a fraction of the data copied across.
Is this because of the incremental only policy?
Are there any risks doing incremental only when it comes to TSM DRM?
Am I convincing myself that changing the incremental only policy to weekly full + daily incrementals is the answer?
Hope this is clear.
Cheers
J
We have a 'forever incremental' backup policy implemented and I have been testing putting in place a DRM process.
It hadn't occurred to me that I might see some odd behaviour with the copy of the primary tape storage pool to the offsite storage pool as part of the DRM process.
My expectation was that as part of this command,
backup stgpool primpool offsitepool wait=yes
ALL data would be copied across from primpool to offsitepool each time it was run.
I have reuse delay set to 7 days and dbb expiry set to 7 days.
On monitoring this, the 1st time it was run I saw ALL data was copied across. However on the 2nd week, only a fraction of the data copied across.
Is this because of the incremental only policy?
Are there any risks doing incremental only when it comes to TSM DRM?
Am I convincing myself that changing the incremental only policy to weekly full + daily incrementals is the answer?
Hope this is clear.
Cheers
J
Thomas Rush
Incremental forever schemes work very well. They greatly reduce the amount of data you need to back up (or replicate). You just need to ensure that part of your backup administration includes periodically creating a synthetic full -- preferably to tape, so you can store it for archival or legal purposes.
ASKER
Hi SelfGovern
Thanks for your response. Yes the incremental forever is used to do just that, minimise the amount we and time taken to backup.
From what I know of a synthetic full, you need to have taken a full backup and then a synthetic full is created from the last full plus the incrementals required. That being the case I am not sure I can even do a synthetic full as we have never ran an actual full (apart from the 1st backup run several years ago).
Cheers
J
Thanks for your response. Yes the incremental forever is used to do just that, minimise the amount we and time taken to backup.
From what I know of a synthetic full, you need to have taken a full backup and then a synthetic full is created from the last full plus the incrementals required. That being the case I am not sure I can even do a synthetic full as we have never ran an actual full (apart from the 1st backup run several years ago).
Cheers
J
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ASKER
Thanks for both comments guys. I'm happy we have all incrementals backups as I have successfully restored to bare metal.
Cheers
J
Cheers
J