[linux-lvm] extending a logical volume
lembark at wrkhors.com
lembark at wrkhors.com
Mon Jan 21 12:43:02 UTC 2002
-- Pierrick PONS <ppons at cvf.fr> on 01/21/02 19:09:31 +0100
> I've read the extending logical volume section and I can't believe this.
> According to the doc, it would be impossible to extend a logical volume
> without unmounting it first.
> I'm using a ext3 (with a 2.4.17 kernel) filesystem and I'd like to extend my
> logical volume without unmounting it first. This would be used on a
> production server, so I can't unmount any logical volume.
>
> I've seen that a ext2online patch does exist, maybe this fonctionnality is
> still implemented in a newer kernel ?
>
> Could you give me, if it exists, a method to extend the size without unmount
> the logical volume ?
>
> Thank's a lot.
Put it another way: You can lvextend a mounted volume.
There isn't any good way to extend the file system while
it's mounted. Adding the cyl groups to a mounted file
system would blow up several parts of the VFS layer.
Since extending the LVM takes O(ms) to finish there
isn't much gain in doing it mounted anyway.
The simplest way to handle it is unmounting, fsck-ing
and re-mounting the thing immediately after your weekly
backup, when users have to be off the system anyway
[if you want to tell me that the system is too important
to offline for a backup I'd strongly suggest finding a
9-story window near the console, it'll be easier to
handle it yourself than have the users do it for you
after a crash looses all of the data].
If the sytsem is used for real-time processing then
simply switch to the backup server for 10 minutes,
extend and validate the system then switch back.
Total time for, say, 100GB file system doubling in
size would be 60 seconds on any reasonably fast I/O
system, nearly all of which is spent extending the
filesystem.
Even HP's LVM -- probably the most forgiving of all --
has to be dismounted for extendfs; lvextend can be run
any time you like.
--
Steven Lembark 2930 W. Palmer
Workhorse Computing Chicago, IL 60647
+1 800 762 1582
More information about the linux-lvm
mailing list