[Dovecot] OT: Re: DoveCot compression to save HDD space

scorch scorch at muse.net.nz
Thu Feb 15 08:08:38 UTC 2007

Host Expert wrote:
> Hi,
> Ok, thanks for comments.
> How effective is ZFS ? I mean yeah, even Windows has file system 
> compression... And what ? Is very poor...

sorry but that's just arrogance over ignorance (sigh). windows NT 
compression is robust, has been available since NT4.0 - i.e. about 10 
years now, and depending on your app needs, an excellent trade-off for 
those who need it. the last time i checked, about 2% additional IO load 
for a busy fileserver with ext RAID5 array  - i.e. 4000+ active smb 
sessions & around 1.3 overall compression factor.

i do not recall any compression-related issues (either in corruption, or 
in performance) in about 5 years of managing 500 0.5Tb+ boxes. you'll 
notice a little more pressure during backup however...
> Question is, what mailserver would be best to run with Solaris/ZFS ?
> Cristian
with a question like that I am sure you'll get as good an answer as your 
"poor performance" comment deserved.

question is, what are your needs? on a dovecot list, i'd imagine the 
answer is already a forgone conclusion :-)

is compression is done on the fly at the disk block level, then you lose 
a small % of CPU, but hopefully gain some back by reduced disk IO. 
you'll need to do extensive testing to see if _your_ situation really 
gains from this.

out of the frying pan & into the fire

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