Date: Mon, 1 Nov 2010 09:27:11 +0100 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: "James R. Van Artsdalen" <james-freebsd-fs2@jrv.org> Cc: freebsd-fs@freebsd.org Subject: Re: ZFS inresponsive. Message-ID: <20101101082711.GG2160@garage.freebsd.pl> In-Reply-To: <4CCDB360.50609@jrv.org> References: <BE2EF896-4990-4A75-9DD4-B0534DFE0B71@pean.org> <20101031104209.771cc47e@r500.local> <AANLkTi=vKSC_wULSzd9k2hF-gDTVeseqyzWrKHsAOMd2@mail.gmail.com> <4CCDB360.50609@jrv.org>
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[-- Attachment #1 --] On Sun, Oct 31, 2010 at 01:20:16PM -0500, James R. Van Artsdalen wrote: > Thomas Zander wrote: > > Same here, same setup. ZFS, GELI, USB. > > It is not a good idea to use USB disks with ZFS. It can cause pool loss. > > Many (most?) USB enclosures use USB<->SATA chips that discard the > SYNC/FLUSH command to the disk. As a result this opens a window of time > where disk writes might be reordered in a way that cause the ZFS > structures to become corrupted. There's no problem in normal operation > but there may be a failure if there is a power loss. > > The log entries in Fabian's note look like a USB SYNC/FLASH failure to > me - that USB enclosure should not be used with ZFS. > > At one time there was talk of "deferred reallocation" in ZFS which would > deal with broken USB enclosures but I don't know if Sun ever got around > to this. Yes, it is implemented in new ZFS. Blocks are not reused for next three transaction groups and one can import a pool by falling back to the last working transaction group if the most recent one is corrupted. -- Pawel Jakub Dawidek http://www.wheelsystems.com pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (FreeBSD) iEYEARECAAYFAkzOed8ACgkQForvXbEpPzRjrwCg6vBC8ojXRxBCrM+nWIyBmWRa UScAoK+tDi2QjskEOXN+I4M3FDVOURA1 =yllR -----END PGP SIGNATURE-----help
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