[OpenIndiana-discuss] Slow zfs writes

[Sašo Kiselkov]

On 02/11/2013 09:54 PM, Robbie Crash wrote:
> If you weren't having any issues with speed and they've progressively
> gotten worse, I'd look at dedup. If you're using dedup, you better make
> sure you've got 2.5GB RAM for every TB of unique data you have, otherwise
> you'll be swapping your dedup tables constantly and your read/write
> performance is going to die.

Also always remember to tune zfs_arc_meta_limit if you have lots of
dedup, since DDT entries count as metadata and by default the meta_limit
is 1/4 of arc_c_max (which for machines with lots of DRAM is ramsize
minus 1GG by default).

Cheers,
--
Saso