Re: lvm on an external enclosure?
On 2009-03-20 16:04, Boyd Stephen Smith Jr. wrote:
On Friday 20 March 2009 09:02:24 Ron Johnson wrote:
1. What kind of problems or issues might I have when trying to boot
and lvm doesn't see a vg? I'm guessing Linux will squawk and
continue booting.
Probably won't even squawk. IIRC, scanning for VGs is done during the boot
process as long as you have LVM installed, whether you are using it or not.
2. More importantly, what about when I power up the external
enclosure, after Linux is already running? Will lvm automagically
recognize the new drives as part of their own vg? Or will I have to
bounce lvm?
You *may* have to run 'vgscan && vgchange -ay', but that should be enough.
Well, that didn't work...
If I umount the fs, then power-down the enclosure, and power it back
up, these are the results:
# vgscan
WARNING: Ignoring duplicate config node: filter (seeking filter)
Reading all physical volumes. This may take a while...
/dev/dm-1: read failed after 0 of 4096 at 2000380952576:
Input/output error
/dev/dm-1: read failed after 0 of 4096 at 2000381009920:
Input/output error
/dev/dm-1: read failed after 0 of 4096 at 0: Input/output error
/dev/dm-1: read failed after 0 of 4096 at 4096: Input/output error
/dev/dm-1: read failed after 0 of 4096 at 0: Input/output error
Found volume group "backup_vg" using metadata type lvm2
Found volume group "main_huge_vg" using metadata type lvm2
# vgchange -a y backup_vg
WARNING: Ignoring duplicate config node: filter (seeking filter)
/dev/dm-1: read failed after 0 of 4096 at 0: Input/output error
1 logical volume(s) in volume group "backup_vg" now active
# mount -v /mnt/backups
mount: wrong fs type, bad option, bad superblock on
/dev/mapper/backup_vg-backup_lv,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
[28515.817160] EXT4-fs: unable to read superblock
[28515.817343] EXT3-fs: unable to read superblock
[28722.859373] EXT4-fs: unable to read superblock
[28722.859458] EXT3-fs: unable to read superblock
Reboot and it works fine.
Failing that, you might have to modify your lvm.conf, but that's only if lvm
is, for some reason, not scanning those block devices for PV metadata.
--
Scooty Puff, Sr
The Doom-Bringer
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