Date: Sat, 1 Jan 2011 14:02:28 +1100 From: Peter Jeremy <peterjeremy@acm.org> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: freebsd-stable@freebsd.org Subject: Re: slow ZFS on FreeBSD 8.1 Message-ID: <20110101030228.GD48579@server.vk2pj.dyndns.org> In-Reply-To: <20101231234747.GA8171@icarus.home.lan> References: <AANLkTinfYync_BG3zV028Or4ZgHe5iQ2tLVd1mn4a0r%2B@mail.gmail.com> <4D1AF388.3080107@infracaninophile.co.uk> <AANLkTim2oV3phJ4bTFL_ENNZYknm7Gjt_3uFdMd1UpYd@mail.gmail.com> <4D1B7431.7070808@infracaninophile.co.uk> <4D1BD8D0.5010402@langille.org> <4D1C4A2D.4020206@infracaninophile.co.uk> <4D1C7929.3040809@langille.org> <20101231233343.GB48579@server.vk2pj.dyndns.org> <20101231234747.GA8171@icarus.home.lan>
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--WfZ7S8PLGjBY9Voh Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2010-Dec-31 15:47:47 -0800, Jeremy Chadwick <freebsd@jdc.parodius.com> w= rote: >Is your ZFS root filesystem associated with a pool that's mirrored or >using raidzX? Currently, mirrored. I'm considering raidz1 at home. Note that my work system is a single pool, whereas I'll use a separate pool for root at home. > What about mismatched /boot content (ZFS vs. UFS)? Can you give me an example of what you mean here. > What about booting into single-user mode? I haven't run into any problems here, though I agree that starting ZFS in single-user mode is a lot messier than starting UFS. >error/mistake). Is it worth the risk? Most administrators don't have >the tolerance for stuff like that in the middle of a system upgrade or >what not; they should be able to follow exactly what's in the handbook, >to a tee. I've been using FreeBSD for long enough that I'm confident to upgrade or similar without blindly following a process. But I agree that FreeBSD should be usable without needing to be a guru. >There's a link to www.dan.me.uk at the bottom of the above Wiki page >that outlines "the madness" that's required to configure the setup, all >of which has to be done by hand. I don't know many administrators who >are going to tolerate this when deploying numerous machines, especially >when compounded by the complexities mentioned above. Root on ZFS is still very bespoke. I agree there's no way you could roll it out across lots of machines at present but I'm happy to hand- craft installs on a few machines. Hopefully, son-of-sysinstall will support ZFS installs (one prerequisite is someone being willing to do the work). >The mmap(2) and sendfile(2) complexities will bite an junior or >mid-level SA in the butt too -- they won't know why software starts >failing or behaving oddly (FreeBSD ftpd is a good example). It just so >happens that Apache, out-of-the-box, comes with mmap and sendfile use >disabled. mmap(2) is a design problem with ZFS - it's present on Solaris as well. IMHO, it's the biggest flaw in ZFS. The sendfile(2) issues haven't bitten me so I haven't studied them as much but I'm aware that some fixes were committed recently. Oh and one root-on-ZFS gotcha that I missed is the lack of gzip support. I spent about =BDday tracking that down - not helped by the lack of any documentation or a useful error message (though there is a comment in the code when you eventually track it down). --=20 Peter Jeremy --WfZ7S8PLGjBY9Voh Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.15 (FreeBSD) iEYEARECAAYFAk0emUQACgkQ/opHv/APuIdcvgCeNZaH8el6KcE6daDvOzjcGuiP NOIAn2hDnXMPwkYgVcBWN3LQsqgU+vEI =bPME -----END PGP SIGNATURE----- --WfZ7S8PLGjBY9Voh--
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