zfs discuss - Aug 2010 - Optimizing performance on a ZFS-based NAS

Thanks to the help from many people on this board, I finally got my
OpenSolaris-based NAS box up and running.

I have a Dell T410 with a Xeon E5504 2.0 GHz (Nehalem) quad-core processor, 8 GB
of RAM. I have six 2TB Hitachi Deskstar (HD32000IDK/7K) SATA drives, set up as
stripes across three mirrored pairs. I have an OCZ Vertex 2 (NOT Pro) 60 GB SSD
(Sandforce-based) for the L2ARC. All seven drives are attached to a Dell SAS
6i/R controller, which is an 8-channel SAS controller based on an LSI chipset.
I''ve enabled dedup and compression on all filesystems of the single
zpool.

Everything is working pretty well, and over NFS, I can get a solid 80 MB/sec if
I''m copying big files. This is adequate, but I am wondering if I can do
any better. I''m only using this box to share between two or three other
machines, in a private (home or lab) network. I think I''ve followed all
of the suggestions I''ve been given; in particular, running 8 GB of RAM
with the 60 GB SSD for the L2ARC should allow full caching of the dedup table. I
ran zilstat.ksh, but it always came up with zeros, which suggests
there''s no point in a ZIL log SSD.

Is there anything left to tune? If so, how do I go about figuring out how to
increase performance? Right now, I''m just copying large files and
looking at the transfer rate as calculated by nautilus, or with iostat -x.
What''s the next thing to do, as far as diagnostics? I''d like
to learn a bit more about the process of optimizing, since I have other such
boxes I want to set up and tune, but with different hardware.
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