Date: Wed, 25 Jun 2008 19:50:04 GMT From: lulf@stud.ntnu.no To: freebsd-geom@FreeBSD.org Subject: Re: misc/124969: gvinum raid5 plex does not detect missing subdisk Message-ID: <200806251950.m5PJo4gf024329@freefall.freebsd.org>
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The following reply was made to PR kern/124969; it has been noted by GNATS. From: lulf@stud.ntnu.no To: Dan Ports <drkp-f@ambulatoryclam.net> Cc: freebsd-gnats-submit@FreeBSD.org Subject: Re: misc/124969: gvinum raid5 plex does not detect missing subdisk Date: Wed, 25 Jun 2008 21:42:06 +0200 Siterer Dan Ports <drkp-f@ambulatoryclam.net>: > >> Number: 124969 >> Category: misc >> Synopsis: gvinum raid5 plex does not detect missing subdisk >> Confidential: no >> Severity: serious >> Priority: medium >> Responsible: freebsd-bugs >> State: open >> Quarter: >> Keywords: >> Date-Required: >> Class: sw-bug >> Submitter-Id: current-users >> Arrival-Date: Wed Jun 25 01:30:01 UTC 2008 >> Closed-Date: >> Last-Modified: >> Originator: Dan Ports >> Release: 6.3-STABLE >> Organization: >> Environment: > FreeBSD clamshell.ambulatoryclam.net 6.3-STABLE FreeBSD 6.3-STABLE =20 > #4: Sat Jun 14 10:05:12 PDT 2008 =20 > root@clamshell.ambulatoryclam.net:/usr/obj/usr/src/sys/CLAMSHELL i386 >> Description: > I am using gvinum to create a RAID 5 array with three drives (i.e. a =20 > single raid5 plex with three subdisks). Recently, one drive failed. =20 > When the drive failed (but was present on boot), the array =20 > continues to work fine, albeit degraded, as one would expect. =20 > However, with the drive removed, gvinum does not properly detect =20 > the plex's configuration on boot: > > 2 drives: > D b State: up /dev/ad11s1d A: 0/474891 MB (0%= ) > D a State: up /dev/ad10s1d A: 0/474891 MB (0%= ) > > 1 volume: > V space State: up Plexes: 1 Size: 463 G= B > > 1 plex: > P space.p0 R5 State: degraded Subdisks: 2 Size: 463 G= B > > 3 subdisks: > S space.p0.s2 State: down D: c Size: 463 G= B > S space.p0.s1 State: up D: b Size: 463 G= B > S space.p0.s0 State: up D: a Size: 463 G= B > > Note that space.p0 has a capacity of 463 GB, the size of the drive, =20 > when it should be twice that. It seems as though the plex isn't =20 > aware that the downed subdisk ever existed. As a result, the volume =20 > is up, but its data is not valid. > > It seems a rather alarming flaw that a RAID 5 array fails to work =20 > correctly when one drive is not present! >> How-To-Repeat: > Create a gvinum raid5 plex with three subdisks, then remove the =20 > drive corresponding to one of them. >> Fix: > No fix, but the following thread appears to be describing the same =20 > problem, and includes an analysis. However, the problem appears to =20 > still exist. (I'm running 6.3-STABLE, and haven't tried either =20 > 7-STABLE or -CURRENT, but a cursory examination of the cvs history =20 > provides no indication that the problem has been fixed in other =20 > branches.) > > http://lists.freebsd.org/pipermail/freebsd-geom/2007-March/002109.html > > I'm willing to poke at this problem a bit more, but am probably the =20 > wrong person to do so since I currently have neither the time nor =20 > any geom experience. > >> Release-Note: >> Audit-Trail: >> Unformatted: > _______________________________________________ > freebsd-bugs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-bugs > To unsubscribe, send any mail to "freebsd-bugs-unsubscribe@freebsd.org" > > This is a known issue, and I've fixed it in patches that are pending review (for a few months now... ;). If it's very critical for you right now, I can create a patch for you, and request a commit for it, but as there are some gvinum restructuring I'd like to get into the tree, I'd rather not fix the same issues twice. but I agree this is a special case, so I'll try get out a fix soon. I'm sorry for the inconvenience. --=20 Ulf Lilleengen
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