[OpenIndiana-discuss] Fwd: poor zfs compression ratio

[Edward Ned Harvey]

> From: Roy Sigurd Karlsbakk [mailto:roy at karlsbakk.net]
> 
> Please keep in mind that dedup in zfs isn't ready for production. If you still
> choose to use it, you'll need massive amounts of memory+L2ARC, 

Even with infinite ram, performance is still terrible without tweaking.  Even with infinite ram and in-depth tweaking, using the latest available in sol11 express (which is later than what's available in OI) ... performance was merely bad, not quite terrible.  On the order of 2x-8x slower than without dedup.  I reserve the word "terrible" for 10x or worse degradation.

I like the concept of online dedup.  If the performance issues are ever resolved, it has the potential to be rock solid screamin' fast.  But it seems those days are a long way off, if ever.

http://mail.opensolaris.org/pipermail/zfs-discuss/2011-May/048185.html
and
http://mail.opensolaris.org/pipermail/zfs-discuss/2011-July/049209.html