[Gllug] Anyone using ZFS?

[Peter Corlett]

general_email at technicalbloke.com wrote:
> I'm considering the fuse-ZFS file system for a new high i/o system I'm
> designing and I was wondering if anyone else has been using it for heavy,
> mostly serial, i/o loads?

"FUSE" and "heavy I/O load" are not usually two phrases seen near each
other. FUSE throughput is disappointing because of all the copying into and
out of userspace.

> I was wondering what kind of raw throughput performance to expect on a 2
> 7200rpm drive system (not CPU bound) compared to the alternative Raid 0 +
> lvm + Ext3 running on the same hardware.

I'd expect performance to roughly halve.

> Also, I am wondering how gracefully performance might degrade with
> concurrency i.e. with loads ranging from from one to say 10 concurrent
> multi gigabyte read/write operations (r-syncs).

ZFS is quite good at not blocking reads when the system is not I/O-starved
due to a load of pending writes in the buffer cache. If your load happens to
fall into that particular situation, you might find that FUSE-ZFS wins over
native ext3.

> Anyone ever built / operated such a system?

No. When I wanted to play with ZFS, I read up about the half-arsed Linux
solution, and just went with Solaris instead. If the non-ZFS bits of Solaris
are outside of your comfort zone, consider virtualising Solaris and
NFS-exporting the ZFS filesystems to Linux.

If you're allergic to Solaris because it's not Free, NetBSD and FreeBSD both
support ZFS without FUSE-style hacks.

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