> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
> boun...@opensolaris.org] On Behalf Of Jim Klimov
> Availability of the DDT is IMHO crucial to a deduped pool, so
> I won't be surprised to see it forced to triple copies. 

Agreed, although, the DDT is also paramount to performance.  In theory, an 
online dedup'd pool could be much faster than non-dedup'd pools, or offline 
dedup'd pools.  So there's a lot of potential here - Lost potential at the 

IMHO, the more important thing for dedup moving forward is to create an option 
to dedicate a fast device (SSD or whatever) to the DDT.  So all those little 
random IO operations never hit the rusty side of the pool.

Personally, I've never been supportive of the whole "copies" idea.  If you need 
more than one redundant copy of some data, that's why you have pool redundancy. 
 You're just hurting performance by using "copies."  And protecting against 
failure conditions that are otherwise nearly nonexistent...  And just as easily 
solved (without performance penalty) via pool redundancy.
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