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VLS9000 - Are we getting much of Dedupe benefits?

Occasional Advisor

VLS9000 - Are we getting much of Dedupe benefits?

We use NetWorker for backups on VLS9000 Tape library, VLS9000 is DeDupe enabled. VLS9000 with 100+ TB available storage.

Over the past 2 months in our data-center, we are seeing only "2.3 to 1" DeDupe ratio (daily incrementals, weekly full backups, two months retention for some savesets, mostly 30 days max). Our remote sites are achieving to the tune of 20-to-1 dedupe ratio over this period. Wondering how we can figure this ..

Our VLS is LTO-3 catridges of 100 GB. Our critical Exchange, SQL, FileShare savesets possibly go into 500 GB sized-savesets (Networker), thus spanning 5 or so tapes worth for these larger savesets.

Can VLS's DeDupe work across multiple tape volumes? One more doubt is - NetWorker may write a saveset to different tape each time saveset is run. In such scenario - how well the DeDupe supposed to work/bring-benefit to us?

Would the DeDupe benefit only if tape-volume is much larger than Saveset, and the saveset is consistently written to the same Tape each time, over-and-again? Or VLS's DeDupe can work at saveset level, or span tapes?

Also one final question - we are really really running low on VLS space at this time (over 95% space used-up). We've already run "Reclaim Space" on VLS - didn't reclaim much. How can we recyle tapes to make more space available ?

Frequent Advisor

Re: VLS9000 - Are we getting much of Dedupe benefits?

- Your screenshot shows issues with the HW compression cards: best have this investigated by HP support by logging a support case and sending them a VLS support ticket.


While they are at it they could look at your deduplication setup.


Yes, deduplication will work across multiple cartridges because the VLS will look at backup objects rather then tapes although there are limits to that.


Storing multiple copies of your data on the same tape is not very good for deduplication. Although VLS deduplication works on the object level, it stores and manages data internally on tape volumes and it can not deduplicate multiple copies of data that exist on a single tape.


More backgroupnd information on VLS deduplication and how it works (as well as tips for Networker) can be found in the Solutions Guide here:

note: link may have limited shelf-life


best regards,