Date: Tue, 28 Aug 2007 23:23:56 +0200 From: Max Laier <max@love2party.net> To: freebsd-current@freebsd.org Cc: Pawel Jakub Dawidek <pjd@freebsd.org>, Pascal Hofstee <caelian@gmail.com> Subject: Re: ZFS kernel panic Message-ID: <200708282324.05834.max@love2party.net> In-Reply-To: <20070828211440.470805B3B@mail.bitblocks.com> References: <20070828211440.470805B3B@mail.bitblocks.com>
next in thread | previous in thread | raw e-mail | index | archive | help
--nextPart3085233.neSCxyxR4m Content-Type: text/plain; charset="iso-8859-6" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Tuesday 28 August 2007, Bakul Shah wrote: > > > The simplest thing to do in case of a write error is to > > > simply ignore it. You *will* catch this problem when you try > > > to read this block. One step better is to do what you > > > suggest. > > > > You can't ignore write error, because application already assumed the > > write succeeded, which can lead to misbehaviour later. ZFS cannot yet > > handle write error, so it panics to preserve data consistency. This > > is the good reaction on ZFS side until skipping bad blocks is not > > implemented. > > If you ignore a write error, the effect is the same as if the > disk block was good on writing but went bad before the first > read. Seems to me this is better than panicing (but of > course not as good as finding an alternate block). This is complete nonsense! As you pointed out earlier zfs doesn't know=20 anything about the nature of the error. There is only one sensible way=20 to deal with a disk error - unless it is transient - and that is stopping=20 all (write) access to the drive. As you can't easily move a mounted=20 drive with opened files into read-only mode, a panic is the only way to=20 make sure. > AFAIK ZFS already uses redundancy for metadata so the > metadata consistency will be maintained. > > > > What happens now when you do use redundancy and there is a > > > write error while writing one of the copies? Does the system > > > panic or is this error ignored? > > > > Don't remember off hand, but component is probably marked as bad and > > vdev group goes to degraded state. You can simulate this easly with > > gnop(8). > > Thanks. It would be good to add some ioctl to allow failing > specific blocks on reads and/or writes. =2D-=20 /"\ Best regards, | mlaier@freebsd.org \ / Max Laier | ICQ #67774661 X http://pf4freebsd.love2party.net/ | mlaier@EFnet / \ ASCII Ribbon Campaign | Against HTML Mail and News --nextPart3085233.neSCxyxR4m Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQBG1JJ1XyyEoT62BG0RApDpAJ4rMr/fCBTJKVwACyZmoptRATPPOwCeMqDC 6JOLk+6u4/idt694tRaVepA= =uE5+ -----END PGP SIGNATURE----- --nextPart3085233.neSCxyxR4m--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200708282324.05834.max>