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Re: [Veritas-bu] Dedupe ratios and checkpoint backups
2011-09-06 15:07:20
To answer your question, we tested both
the NBU 5000 (Symantec) and the DD860 (Data Domain) and the differences
couldn't be more stark. I was using a 30 minute checkpoint interval.
I never achieved anything better than 15:1 from the NBU5000 (which
isn't bad). The DD860 hit 39:1 at the time I disabled all of the
policies. This was running daily full backups on an array of different
servers (DB2, Windows file servers, UNIX file servers, and Siebel app servers)
over the course of 2 months.
The NBU5000 is a fixed block device,
the DD860 a variable block device. There is no way of knowing if
checkpoints were the culprit for the NBU5000 getting the lesser ratio,
but it does present a plausible theory.
| From:
| scott.george AT parker DOT com
|
| To:
| "veritas-bu AT mailman.eng.auburn DOT edu"
<veritas-bu AT mailman.eng.auburn DOT edu>
|
| Date:
| 09/06/2011 02:54 PM
|
| Subject:
| Re: [Veritas-bu] Dedupe ratios and checkpoint
backups
|
| Sent by:
| veritas-bu-bounces AT mailman.eng.auburn DOT edu |
If at all, this would probably affect
fixed-block solutions more than the variable-block ones. The variable-blocked
solutions would continue to look for identical blocks, but in different
positions of the data stream.
| From:
| "Stafford, Geoff"
<GStafford AT barclaycardus DOT com>
|
| To:
| "veritas-bu AT mailman.eng.auburn DOT edu"
<veritas-bu AT mailman.eng.auburn DOT edu>
|
| Date:
| 09/06/2011 02:45 PM
|
| Subject:
| [Veritas-bu] Dedupe ratios and checkpoint
backups
|
| Sent by:
| veritas-bu-bounces AT mailman.eng.auburn DOT edu |
Just wondering if anyone has done testing or seen documentation (from any
dedupe vendor) regarding the usage of enabling checkpoints on backups that
are being deduplicated? I would think that the introduction of checkpoints
every X minutes into the datastream would interrupt the continuity of the
data and make it seem more unique thus negatively affecting dedupe ratios
but I’m wondering by how much. Most, if not all, of the variable
length guys have the ability to ‘re-align’ themselves to the start of
the files so I would think it might be more pronounced on large files vs
your average server but I’m just thinking out loud.
Anyone seen a recommendation or actually tested themselves?
_______________________________________________________
Barclays
www.barclaycardus.com
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