Checkpoints create a new file for each checkpoint.
On 9/7/2011 1:17 PM, Rusty Major wrote:
I have always understood it that Checkpoints were saved in a log on
the client and, therefore, wouldn't affect dedupe ratios at all. I
haven't ever verified that, nor did a quick search yield anything.
-Rusty
*From:*veritas-bu-boun...@mailman.eng.auburn.edu
<mailto:veritas-bu-boun...@mailman.eng.auburn.edu>
[mailto:veritas-bu-boun...@mailman.eng.auburn.edu
<mailto:veritas-bu-boun...@mailman.eng.auburn.edu>] *On Behalf Of
*Lightner, Jeff
*Sent:* Tuesday, September 06, 2011 3:23 PM
*To:* scott.geo...@parker.com <mailto:scott.geo...@parker.com>;
veritas-bu@mailman.eng.auburn.edu
<mailto:veritas-bu@mailman.eng.auburn.edu>
*Subject:* Re: [Veritas-bu] Dedupe ratios and checkpoint backups
Haven't done any comparisons but we use checkpoint for our big ERP DB
(near 6 TB) backup and still get good compression ratios. There is
nothing that has made me think I need to look at it or tweak it to get
better. I'd say the benefit of not having to restart a huge backup
from scratch offered by checkpoints would outweigh deduplication ratio
issues unless you have infinite time to run backups.
------------------------------------------------------------------------
*From:*veritas-bu-boun...@mailman.eng.auburn.edu
<mailto:veritas-bu-boun...@mailman.eng.auburn.edu>
[mailto:veritas-bu-boun...@mailman.eng.auburn.edu
<mailto:veritas-bu-boun...@mailman.eng.auburn.edu>] *On Behalf Of
*scott.geo...@parker.com <mailto:scott.geo...@parker.com>
*Sent:* Tuesday, September 06, 2011 3:06 PM
*To:* veritas-bu@mailman.eng.auburn.edu
<mailto:veritas-bu@mailman.eng.auburn.edu>
*Subject:* Re: [Veritas-bu] Dedupe ratios and checkpoint backups
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.geo...@parker.com <mailto:scott.geo...@parker.com>
To:
"veritas-bu@mailman.eng.auburn.edu
<mailto:veritas-bu@mailman.eng.auburn.edu>"
<veritas-bu@mailman.eng.auburn.edu
<mailto:veritas-bu@mailman.eng.auburn.edu>>
Date:
09/06/2011 02:54 PM
Subject:
Re: [Veritas-bu] Dedupe ratios and checkpoint backups
Sent by:
veritas-bu-boun...@mailman.eng.auburn.edu
<mailto:veritas-bu-boun...@mailman.eng.auburn.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" <gstaff...@barclaycardus.com
<mailto:gstaff...@barclaycardus.com>>
To:
"veritas-bu@mailman.eng.auburn.edu
<mailto:veritas-bu@mailman.eng.auburn.edu>"
<veritas-bu@mailman.eng.auburn.edu
<mailto:veritas-bu@mailman.eng.auburn.edu>>
Date:
09/06/2011 02:45 PM
Subject:
[Veritas-bu] Dedupe ratios and checkpoint backups
Sent by:
veritas-bu-boun...@mailman.eng.auburn.edu
<mailto:veritas-bu-boun...@mailman.eng.auburn.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?
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