ZFS cpu requirements, with/out compression and/or dedup

[Quartz]

> from what i read the status of dedup is not that clear and seems there are
> bugs and better to avoid it?

There aren't [m]any legitimate bugs with dedup, the problem is that it 
consumes metric assloads of ram, on the order of 2-5GB per TB of disk 
space (this is in addition to whatever the ARC eats). If you run out of 
ram performance jumps off a cliff. It's also 'permanent' in the sense 
that you have to turn it on with the creation of a dataset and can't 
disable it without nuking said dataset. The issue of "bugs" are probably 
from people experiencing file corruption because they enabled only block 
checksums without also exact verification, and don't understand hash 
collisions.


> so according to 1-3 above what cpu requirements i need?

Not much. CPU only really takes a hit when you turn on gzip compression 
and crank it up to high levels.


> supermicro c2750/3/5/8 enough to run system of 20TB /40TB with 1-3 above?
> if dedup IS enabled would it still work fine?

Probably not. That board only supports up to 64GB of ram. 20TB of disk 
space with dedup will require like 50-100 GB of ram, and 40TB will need 
a good 90GB at least.