[linux-lvm] LVM 1.0.7, kernel 2.4.21 and snapshots over ext3 filesystem

[Wolfgang Weisselberg]

Alberto Picon Couselo wrote 42 lines:

> Wolfgang, thank you very, very much for your advice.

You are welcome.

> Now, I'm able to create a snapshot and mount it, but I receive a strange
> warning message (even if I mount it readonly):

> $~# mount -t ext3 -r /dev/storage/snap /mnt/temporal/
> Can't write to read-only device 3a:04
> kjournald starting.  Commit interval 5 seconds
> Can't write to read-only device 3a:04
> EXT3-fs: mounted filesystem with ordered data mode.

Well ... it is saying: 
    "Hey, this is a read-only fs!"
twice.  Once after mounting and once after starting the
kernelthread for the journalling.

Now, the snapshots are read-only :-) so the complaint is
valid, but not impressive.  I get even a few more warnings in
my syslog (but none to STDOUT/STDERR):

| kernel: Can't write to read-only device 3a:06
| kernel: kjournald starting.  Commit interval 5 seconds
| kernel: EXT3-fs: lvm(58,6): orphan cleanup on readonly fs
| kernel: ext3_orphan_cleanup: deleting unreferenced inode 17
| kernel: ext3_orphan_cleanup: deleting unreferenced inode 163842
| kernel: EXT3-fs: lvm(58,6): 2 orphan inodes deleted
| kernel: EXT3-fs: recovery complete.
| kernel: lvm - lvm_map: ll_rw_blk write for readonly LV /dev/base_vg/SNAP-test
| last message repeated 10 times
| kernel: Can't write to read-only device 3a:06
| last message repeated 2 times
| kernel: EXT3-fs: mounted filesystem with ordered data mode.

Of course, the FS was not clean when I snap-shot it.  (bang!)

> Anyway, the snapshot is mounted and it's visible... So, it seems to
> work... What's your opinion about this?

AFAICT it works.

-Wolfgang