[OpenIndiana-discuss] Fwd: poor zfs compression ratio

[Krishna PMV]

Resending as my previous email didn`t get through the list.  Can someone
please advice how we can improve compression ratio here? Thanks!

---------- Forwarded message ----------
From: Krishna PMV <krishna.pmv at gmail.com>
Date: Fri, Oct 28, 2011 at 10:41 AM
Subject: poor zfs compression ratio
To: openindiana-discuss at openindiana.org


Hey,

We are trying to backup our emails by copying (via rsync) them to a
different storage server where we have recently installed openindiana[1] so
we can take advantage of inbuilt compression and deduplication features of
zfs but to our surprise, the compression ratio seem to be pretty low. We
ran different tests as follows[2] but none of them were anywhere close to
vanilla compression (with gzip command) of mdbox ( dovecot`s own mailbox
format) files themselves  or dovecot`s inbuilt compression[3] . Any ideas
how we could improve zfs`s compression ratio here?  Thanks!


[1] uname -a
SunOS backup-us1 5.11 oi_148 i86pc i386 i86pc Solaris

[2].
a) default compression (=lzjb) and dedup=on
zfs get compressratio tank/testingdeduponfromjr1
NAME                        PROPERTY       VALUE  SOURCE
tank/testingdeduponfromjr1  compressratio  1.13x  -


b) default compression (=lzjb) and dedup=off
 zfs get compressratio tank/testingdedupofffromjr1
NAME                         PROPERTY       VALUE  SOURCE
tank/testingdedupofffromjr1  compressratio  1.12x  -

c) compression=gzip(=gzip6) and dedup=on
 zfs get compressratio tank/testingdeduponandgzipfromjr1
NAME                               PROPERTY       VALUE  SOURCE
tank/testingdeduponandgzipfromjr1  compressratio  1.61x  -

d) compression=gzip-9 and dedup=on
zfs get compressratio tank/testingdedupoffandgzip9fromjr1
NAME                                 PROPERTY       VALUE  SOURCE
tank/testingdedupoffandgzip9fromjr1  compressratio  1.66x  -


3) http://wiki2.dovecot.org/Plugins/Zlib