Date: Thu, 21 Sep 2006 15:43:03 -0500 From: Eric Anderson <anderson@centtech.com> To: James Lauser <james@jlauser.net> Cc: freebsd-fs@freebsd.org Subject: Re: Snapshot corruption on 6.1/amd64 Message-ID: <4512F957.2090205@centtech.com> In-Reply-To: <854C78DB-2099-4DA5-9E3B-F30D6947C532@jlauser.net> References: <854C78DB-2099-4DA5-9E3B-F30D6947C532@jlauser.net>
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On 09/21/06 14:59, James Lauser wrote: > Hello. > > I've been having some trouble with snapshots on my FreeBSD 6.1/amd64 > system. Basically, I have this system set up with a 3ware RAID card > and several disks, and use it to collect backups from my other > FreeBSD server (sparc64) and three Macs via rsync.. > > Every night, I have a script generate a snapshot of the RAID's file > system, and those snapshots are kept on the system for one week > before being removed (i.e. there are always 7 snapshots present on > the system), so I can recover files that were accidentally removed or > changed. > > The problem is that when a large number of files are removed or > changed on the file system, the corresponding files in the snapshot > get corrupted. This, obviously, makes the snapshots quite useless. > > After some searching, I've found a bug report filed last year that > describes this problem exactly, though the log of that report does > not suggest that anything has been done with it. That report is at > http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/90512 > > Any help would be greatly appreciated. A test I ran showing the > problem, plus the output of uname -a and dmesg.boot is attached. > > Thanks in advance. > Sledge# cd /raid > Sledge# touch foo > Sledge# ls -l foo > -rw-r--r-- 1 root wheel 0 Sep 18 14:07 foo > Sledge# mksnap_ffs /raid /raid/.snap/snap > Sledge# rm foo > Sledge# mdconfig -a -t vnode -f /raid/.snap/snap -u 4 > WARNING: opening backing store: /raid/.snap/snap readonly > Sledge# mount -r /dev/md4 /mnt > Sledge# cd /mnt > Sledge# ls -l foo > ls: foo: Bad file descriptor > Sledge# > Sledge# > Sledge# > Sledge# uname -a > FreeBSD Sledge.jlauser.net 6.1-RELEASE-p6 FreeBSD 6.1-RELEASE-p6 #4: Wed Sep 6 23:30:56 EDT 2006 root@Sledge.jlauser.net:/usr/obj/usr/src/sys/GENERIC amd64 Hmm.. Interesting, it seems to work fine for me: [root@neutrino /tmp]# dd if=/dev/zero of=TESTDISK bs=1m count=100 100+0 records in 100+0 records out 104857600 bytes transferred in 3.390829 secs (30923882 bytes/sec) [root@neutrino /tmp]# mdconfig -a -t vnode -f ./TESTDISK md0 [root@neutrino /tmp]# newfs -U /dev/md0 /dev/md0: 100.0MB (204800 sectors) block size 16384, fragment size 2048 using 4 cylinder groups of 25.02MB, 1601 blks, 3264 inodes. with soft updates super-block backups (for fsck -b #) at: 160, 51392, 102624, 153856 [root@neutrino /tmp]# mount /dev/md0 /mnt [root@neutrino /tmp]# touch /mnt/foo [root@neutrino /tmp]# mksnap_ffs /mnt/ /mnt/.snap/snap [root@neutrino /tmp]# mdconfig -a -t vnode -f /mnt/.snap/snap WARNING: opening backing store: /mnt/.snap/snap readonly md1 [root@neutrino /tmp]# mount -r /dev/md1 /mnt2 [root@neutrino /tmp]# cd /mnt2 [root@neutrino /mnt2]# ls -l foo -rw-r--r-- 1 root wheel 0 Sep 21 15:37 foo [root@neutrino /mnt2]# Can you unmount /raid, and do an fsck -y /raid and make sure it's clean? Also - are you using quotas? How big is the filesystem? Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology Anything that works is better than anything that doesn't. ------------------------------------------------------------------------
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