Hi list readers, the archive has various messages about this topic but I am not sure if my problem is caused by xfs and the lvm snapshot or not. I came a long way to this place. Let me elaborate on this a little. First of all my system config: I am using Gentoo Linux, kernel 2.6.16-gentoo-r7, device-mapper-1.02.07, lvm2-2.02.06, xfsprogs-2.7.11 and on the test box: 2.6.17-gentoo-r4, device-mapper-1.02.08, lvm2-2.02.07, xfsprogs-2.7.11 My intension is to make full system (just everything) backups of a reasonably busy mailserver. I am using cyrus imap as pop/imap server, postfix as smtpd and amavisd-new as malware scanner. Pretty common setup. I wrote a backup script that uses the hard linking techique of rsync (described e.g. here http://www.mikerubel.org/computers/rsync_snapshots/). Before starting rsync I made lvm snapshots of /var and /var/spool/imap. These are the most busiest partitions. The output of rsync showed errors and everybody wants his backup to be the same as the original data, right? Thus I wrote another script that verifies source against destination data. I can provide the code for it. The script fails when doing the md5sum check. Here is the output: md5sum: WARNING: 8 of 70769 computed checksums did NOT match md5sum check failed ./amavis/db/__db.001: FAILED ./amavis/db/__db.002: FAILED ./amavis/db/__db.003: FAILED ./imap/db/__db.001: FAILED ./imap/db/__db.002: FAILED ./imap/db/__db.003: FAILED ./imap/db/__db.004: FAILED ./imap/db/__db.005: FAILED or like so: md5sum: WARNING: 9 of 72522 computed checksums did NOT match md5sum check failed ./amavis/db/__db.001: FAILED ./amavis/db/__db.002: FAILED ./amavis/db/__db.003: FAILED ./amavis/quarantine/spam-74v2QeUbeNRR.gz: FAILED ./imap/db/__db.001: FAILED ./imap/db/__db.002: FAILED ./imap/db/__db.003: FAILED ./imap/db/__db.004: FAILED ./imap/db/__db.005: FAILED My first attempt to solve this was to stop the daemons that write these files. I stopped amavisd-new and cyrus, took the lvm snapshot and restarted the services. Then I did the backup. But the verify was still failing. I asked myself why only that few files out of more than 70000 are failing the test. I took a closer look and compared the first file manually. The size was equal but "cmp" said that the files were differing in the first byte. Then I thought it was a kind of a file system caching issue and I put some "sync" commands after stopping the daemons and before taking the lvm snapshot. The result was that only two files were failing the md5sum check. However two files failing are two files too much. Somehow I found the xfs_freeze command and I thought that it must be the solution of my problems. Unfortunately I locked the mailserver ;) and had to hard reset it, because lvcreate didn't give me the prompt back. Hitting CTRL-C neither. >From the archive I have learned that xfs_freeze shouldn't be necessary with lvm2 anymore. Also I have read something about versioning problems. I posted mine above, so maybe it's a version issue? If not, I also read about the dmsetup command. I played around a little with dmsetup and found a working combination of commands. Bit I am not sure if this is the way one can do this. dmsetup suspend vg0-var xfs_freeze -f /var dmsetup resume vg0-var lvcreate -s -L 1G -n snapvar /dev/vg0/var xfs_freeze -u /var # do backup from the snapshot lvremove -f /dev/vg0/snapvar To me it doesn't sound good issueing these commands. Just a feeling ;). Does there remain any other source of the above md5sum errors? I believe not, because the other 70,000 files were checked and proved to be right. Any hints? TIA and kind regards, Timo _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
