TSM DRM behaviour with incremental backups
Posted on 2013-05-28
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.