Hi Yaron

I know that NetWorker has a default block size for each of its output devices.  
This default block size can be overridden; details on this are in the NetWorker 
Administration Guide.

Does ZFS have a specific block size that it deduplicates?  If so, could it be 
that the NetWorker default block size for the AFTD device is not the same as, 
or a multiple of, the ZFS default block size?

tl

-----Original Message-----
From: EMC NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On 
Behalf Of Yaron Zabary
Sent: Sunday, March 14, 2010 3:59 PM
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: [Networker] ZFS deduplication.


   A few days ago I read a post to EMC's Networker forum by Nicholas 
Bone (https://community.emc.com/thread/99839?tstart=0). He reported a 
test he performed with AFTD which was running on top of ZFS with dedup. 
Unfortunately, he wasn't able to get any reasonable dedup ratios (1.03 
for three full savesets of the the same file system). My conclusion was 
that Networker does not align files at block level, which confuses the 
ZFS dedup code. Is anyone familiar with some flag or any configuration 
option which will convince save or AFTD to do the right thing so that 
ZFS will be able to find identical blocks ?

-- 

-- Yaron.

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