I wouldn't bother with a dedup device for two main reasons.
Firstly, these will quickly be made redundant with Avamar integration with
NetWorker. I can't be sure, but I doubt that this will even be a licensed
feature, as Veritas already include this functionality for free with NetBackup
- of course, NetBackup is generally a bit more expensive than NetWorker, so who
knows for sure?
Secondly, you're adding a virtualisation layer between NetWorker and the disk.
Personally, I've never been particularly impressed with NetWorker's disk
handling, given that it still treats them as tape devices and given the number
of staging and cloning problems that yzou see - these are just managed recovery
and backup operations, and shouldn't be particularly problematic. Not only do
they have a disproportionally high number of problems even when NetWorker knows
where the data is, that's going to be multiplied if the dedup device is
anything other than 100% reliable.
Also, though this issue will remain in any case with dedup, if one block on
disk is damaged, how many files is that likely to hit?
That's my personal opinion, obviously. I'll soon be working with network dedup
devices, and they're highly impressive at improving network performance. The
difference I see there is that the data you're dedup/reduping is likely to be
used immediately, and you'll quickly identify problems. In the case of backup
and restore though, you may not find out about problems for a long time, and
those problems could hit a lot of files.
Cheers,
Stuart.
________________________________
From: EMC NetWorker discussion on behalf of Brett Monroe
Sent: Thu 01/11/2007 15:47
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: [Networker] Data De-Duplication product info
Hey all,
We are currently in the planning phase of dramatically transforming out data
center's backup environment from the stone age (direct-attach tape drives on
all servers doing fulls every night) to a more modern approach of
centralization. We are also looking to implement a data De-Duplication
device in the mix but the offerings seem...immature. I was wondering if any
of you fine folks have any experience with any of de-duping technology
whether it's client based software (Avamar) or something that sits in front
of a backup disk device (Data Domain, Diligent, etc). I'd be very
interested in hearing what your experiences have been.
Thanks
--Brett
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