Date: Mon, 15 Feb 2010 10:03:40 -0800 From: Freddie Cash <fjwcash@gmail.com> To: freebsd-stable@freebsd.org Subject: Re: More zfs benchmarks Message-ID: <b269bc571002151003v6a1b630chdb0acb2c0ccb2fc7@mail.gmail.com> In-Reply-To: <4B7989AE.1050203@witchspace.com> References: <EC10D2E9-04C7-4976-B377-62E79D9BE47A@witchspace.com> <4B7989AE.1050203@witchspace.com>
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On Mon, Feb 15, 2010 at 9:51 AM, Jonathan Belson <jon@witchspace.com> wrote: > On 14/02/2010 17:28, Jonathan Belson wrote: > >> After reading some earlier threads about zfs performance, I decided to >> test my own server. I found the results rather surprising... >> > > Thanks to everyone who responded. I experimented with my load.conf > settings, leaving me with the following: > > vm.kmem_size="1280M" > vfs.zfs.prefetch_disable="1" > > That kmem_size seems quite big for a machine with only (!) 2GB of RAM, but > I wanted to see if it gave better results than 1024MB (it did, an extra > ~5MB/s). > For a system with 2 GB of RAM, and possibly slow harddrives, consider adding a "cache" vdev (L2ARC). The 4 GB and larger USB flash drives are getting to be pretty fast for reads (which is what the L2ARC is for). On my home system, which is a 32-bit FreeBSD 8-STABLE box with a 3.0 GHz P4 and 2 GB of RAM, adding a 4 GB Transcend JetFlash has done wonders for improving stability and read speed. Most of my apps now load from the USB stick instead of the slow raidz1 vdev (3x 120 GB SATA drives). Haven't done any real benchmarks yet (still upgrading to KDE 4.4), but things feel smoother, and it hasn't locked up since adding the USB stick. On this box, running ktorrent 24/7 used to lock up the box after 3-5 days (can't even toggle numlock). This box uses a kmem_max of 1 GB, and an arc_max of 512 MB. With a 4 GB L2ARC. :) -- Freddie Cash fjwcash@gmail.com
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