Re: [Veritas-bu] Measuring redundant backup data

Maybe not just site specific but vendor specific?

We’re using Data Domain rather than PureDisk. My comments about how much is being deduped was based both on our experience and those posted by others on this list when I’d asked the question before we bought the DD units.

Also I saw rather good presentation on data deduplication at the Atlanta Unix Users Group meeting last month from the EMC folks. They pointed out that one has to really understand a lot of what is meant by deduplication (i.e. which methodology it uses). The Data Domain stuff uses block level deduplication.

There was another vendor that saw discussion about Data Domain here before we got it and sent me some literature – my read of that suggested I’d have to buy storage equal to the existing arrays so it didn’t seem like much of a savings to me.

From: Ed Wilts [mailto:ewilts AT ewilts DOT org]
Sent: Tuesday, April 08, 2008 10:05 PM
To: Jeff Lightner
Cc: Michaels, Keith R; veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Measuring redundant backup data

On Tue, Apr 8, 2008 at 5:57 PM, Jeff Lightner <jlightner AT water DOT com> wrote:

I don't know a way to measure how much is "redundant" easily. Maybe the
much vaunted Aptare would have that - I'll wait for their fan club to
comment on that. :-)

Not a chance - Aptare just gets job status and doesn't ever see the backup data.

So far it appears to us the deduplication devices are living up to or
exceeding expectations.

That's purely site specific. With PureDisk backing up our remote sites, I think we're under 5:1 but we're still building up the generation count. When we pointed some of larger main campus data at it, it wasn't even that high - nowhere near high enough to justify the cost.

Some vendors will let you eval you a unit - that's the only way to know how well you're going to dedupe because it is so client specific. If you have a ton of application servers with mostly OS and little application, you're going to de-dupe extremely well. If you have 1 file server full of TIFF data that never stays around very long, you won't de-dupe well at all.

--
Ed Wilts, Mounds View, MN, USA
mailto:ewilts AT ewilts DOT org

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