On Fri, Jun 04, 2010 at 12:37:01PM -0700, Ray Van Dolson wrote:
> On Fri, Jun 04, 2010 at 11:16:40AM -0700, Brandon High wrote:
> > On Fri, Jun 4, 2010 at 9:30 AM, Ray Van Dolson <rvandolson@xxxxxxxx> wrote:
> > > The ISO's I'm testing with are the 32-bit and 64-bit versions of the
> > > RHEL5 DVD ISO's. While both have their differences, they do contain a
> > > lot of similar data as well.
> > Similar != identical.
> > Dedup works on blocks in zfs, so unless the iso files have identical
> > data aligned at 128k boundaries you won't see any savings.
> > > If I explode both ISO files and copy them to my ZFS filesystem I see
> > > about a 1.24x dedup ratio.
> > Each file starts a new block, so the identical files can be deduped.
> > -B
> Makes sense. So, as someone else suggested, decreasing my block size
> may improve the deduplication ratio.
> recordsize I presume is the value to tweak?
Yes, but I'd not expect that much commonality between 32-bit and 64-bit
Do the same check again with the ISOs "exploded", as you say.
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