Date: Sat, 11 Oct 2008 23:30:53 +0100 From: Pegasus Mc Cleaft <ken@mthelicon.com> To: freebsd-hackers@freebsd.org Subject: Re: ZFS boot Message-ID: <200810112330.53214.ken@mthelicon.com> In-Reply-To: <Pine.GSO.4.64.0810111349540.16737@zeno.ucsd.edu> References: <E1KoeVm-000ELP-4b@cs1.cs.huji.ac.il> <b269bc570810111337l4a8f9fc9yfc6f5959d7c971fd@mail.gmail.com> <Pine.GSO.4.64.0810111349540.16737@zeno.ucsd.edu>
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On Saturday 11 October 2008 21:53:35 Nate Eldredge wrote: > On Sat, 11 Oct 2008, Freddie Cash wrote: > > On 10/11/08, Matthew Dillon <dillon@apollo.backplane.com> wrote: > >> With regards to the traditional BSD partitioning scheme, having a > >> separate /usr, /home, /tmp, etc... there's no reason to do that > >> stuff any more with ZFS (or HAMMER). > > > > As separate partitions, no. As separate filesystems, definitely. > > > > While HAMMER PFSes may not support these things yet, ZFS allows you to > > tailor each filesystem to its purpose. For example, you can enable > > compression on /usr/ports, but have a separate /usr/ports/distfilles > > and /usr/ports/work that aren't compressed. Or /usr/src compressed > > and /usr/obj not. Have a small record (block) size for /usr/src, but > > a larger one for /home. Give each user a separate filesystem for > > their /home/<username>, with separate snapshot policies, quotas, and > > reservations (initial filesystem size). > > All this about ZFS sounds great, and I'd like to try it out, but some of > the bugs, etc, listed at http://wiki.freebsd.org/ZFSKnownProblems are > rather alarming. Even on a personal machine, I don't want these features > at the cost of an unstable system. Is that list still current? I dont know if that list is completely accurate any more, but I can tell you from my own personal experience with ZFS that it has been quite good. I have two servers (one is my test-bed at home) and the other is a production server running mostly mysql at work and I have never experienced the dead-locking problem. > > FWIW, my system is amd64 with 1 G of memory, which the page implies is > insufficient. Is it really? This may be purely subjective, as I have never bench marked the speeds, but when I was first testing zfs on a i386 machine with 1gig ram, I thought the performance was mediocre. However, when I loaded the system on a quad core - core2 with 8 gigs ram, I was quite impressed. I put localized changes in my /boot/loader.conf to give the kernel more breathing room and disabled the prefetch for zfs. #more loader.conf vm.kmem_size_max="1073741824" vm.kmem_size="1073741824" vfs.zfs.prefetch_disable=1 The best advice I can give is for you to find an old machine and test-bed zfs for yourself. I personally have been pleased with it and It has saved my machines data 4 times already (dieing hardware, unexpected power bounces, etc) As a side note, my production machine boots off a dedicated UFS drive (where I also have a slice for the swap). /usr, /var, /var/db and /usr/home are zfs. My test server at home only has /usr/home as zfs. I found it easier for me, when I kill the home machine to just do a reload/rebuild of the OS, rebuild the applications, and rechown/grp the home directories. Peg
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