I've found that snapshot is unreliable. We can consistently corrupt the database by creating a snapshot. Yes, you heard it, snapshot (for us) corrupts the _source_. Also, I have had no response from the maintainers, perhaps because it is LVM1 . . . but I really don't know. Fortunately, we have the luxury of being able to do this at the hardware level (an IBM ESS, otherwise known as Shark) with a process that is exactly the same as snapshot. The best thing is to use a database that is able to backup itself while online. On that note, if you are using reiserfs, it balks _badly_ at being a readonly filesystem. Even if you mount it readonly, it still wants write access to the journal. We have a situation in our shop where linux can not access the disks in read/write mode. For those filesystems that were bootable, we cannot use reiserfs. I'm guessing the same is true in this situation. With ext3, try mounting it as an ext2 filesystem. It may be having trouble with the journal also. -----Original Message----- From: John Seifarth [mailto:lists@waw.be] Sent: Wednesday, December 31, 2003 6:44 PM To: linux-lvm@sistina.com Subject: Cannot mount ext3 snapshot I've serious problem with snapshots here. I've used LVM on other machines, but had not yet tried the snapshot feature. I just built a machine with a 3ware SATA RAID controller, and used LVM on the /dev/sda device it presents. When I try to mount a snapshot, I get a message: Mount: wrong fs type, bad option, bad superblock on /dev/fast/snap, or too many mounted file systems Is the problem dependent on the RAID controller? I created a VG and LV based on a normal ATA partition, and got the same error message on attempting to mount. I tried on my previous machines, and they allow mounting snapshots with no problem. WORKING CONFIGURATION Slackware 8.1 linux kernel 2.4.22 mount version mount-2.11r LVM version in kernel 1.0.5+(22/07/2002) LVM tools version vgdisplay --version gives 1.0.7 Filesystem reiserfs NON-SNAPSHOT MOUNTING CONFIGURATION Slackware 9.1 linux kernel 2.4.23 mount version mount-2.12 LVM version in kernel 1.0.7(28/03/2003) LVM tools version vgdisplay --version gives 1.0.7 Filesystem: ext3 ADDITIONAL TESTS dmesg shows for ext3 file systems EXT3-fs: INFO: recovery required on readonly filesystem EXT3-fs: write access unavailable, cannot proceed and doesn't mount for reiserfs Can't write to read-only device 3a:03 repeated several times, but mounts finally To get snapshots to work with ext3, I must first unmount the source volume and create the snapshot. Then I can get the snapshot to mount. Trying again later, making a snapshot with the volume mounted, the snapshot fails to mount. Once I made a snapshot of the unmounted reiserfs volume, subsequent snapshots of the mounted reiserfs volume appear to mount as expected. This appears to hold true on the IDE disk partition and the 3ware raid card disk device. Anyone else notice this type of behavior with snapshots? Anyone else using snapshots for database backups? Thanks, John -- __________________________________________________________________ John Seifarth http://www.waw.be/waw/ Words & Wires SPRL lists@waw.be Computer Consulting & Language Services Voice: (+) 32-2-660-3943 1160 Brussels, Belgium Fax: (+) 32-2-675-3922 _______________________________________________ linux-lvm mailing list linux-lvm@sistina.com http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ _______________________________________________ linux-lvm mailing list linux-lvm@sistina.com http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/