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Monday, 15 December 2014

Odd behaviour on a large incremental backup job

I've been investigating why one of my customer's incremental backups is so large.

They are doing incrementals forever -- they run one full backup a long time ago, and have been synthesising full backups each weekend ever since out of their incremental backups.

One backup object has 500GB backed up every night, and as it's a small third-world country branch office, this didn't make much sense.

When I went into the session (e.g. by pretending to start a restore) and tried to find which files had changed, I came up blank. The modification time of most of the files was way in the past. There was no reason they should have been backed up.

Adding to the mystery, when I turned off "Do not use archive attribute" the incremental shrunk down to something sensible.

So either Data Protector isn't resetting the archive attribute flag in this particular situation, or something else is turning the archive flag on.

The file server in question is running Win2k8 R2 with a Data Protector 8.11 connecting to a 9.01 cell manager. I'll have to upgrade it confirm it's still a problem, but I suspect it will continue to be.


Greg Baker is an independent consultant who happens to do a lot of work on HP DataProtector. He is the author of the only published books on HP Data Protector (http://www.ifost.org.au/press/#dp). He works with HP and HP partner companies to solve the hardest big-data problems (especially around backup). See more at IFOST's DataProtector pages at http://www.ifost.org.au/dataprotector