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Re: Now that I have working box, any problems with LVM?

hdv@jadev.org (J.A. de Vries) writes:

> Hi list,
> I was considering to use LVM on my brand new box now that is working. I
> have never used it before, but want to learn about it. (How's that for a
> reason? }:-) Before I start this little endeavor I'd like to ask if
> anyone knows of any caveats of using LVM[12] on debian-amd64. Also what
> are the feelings on the list of adding root to LVM? This is not a
> critical box in any way, but as it is supposed to be a server stability
> is of some concern.
> Grx HdV

Some hints:

1. you can't boot from lvm so make / or /boot not on lvm (I prefer the

2. /etc/lvm/backup might be needed for recovery. If you want / on lvm
then link /etc/lvm to somewhere else (e.g. /boot/lvm).

3. /dev on lvm creates deadlocks when doing a snapshot or pvmove (or
used to do with prior versions). Best way is to have / not on
lvm. devfs or udev might do the trick too.

4. don't use lvm1. Thats basicaly just there to allow using old volume

5. If you create a / outside the lvm (and I strongly suggest doing
that) make it not to small and not to big (somewhere between
100-500Mb) and at the begining of the disk. You might want to copy a
few extra things to /bin or /sbin that usualy reside in /usr. E.g. in
case something does go wrong with the lvm (and then /usr won't be
there) an editor might be usefull. Copy nano or zile to /bin.

6. If / is on lvm and something does go wrong remeber that / won't be
mountable. Have a rescue system available. e.g. a bootable usb stick
with busybox, an editor, /etc/lvm/*, .... Actualy those are very
usefull in any case.

Apart from those hints I have only one problem with lvm on my amd64:
Reconstructing a raid5 on lvm only does 1MB/s (instead of 50 MB/s
vithout lvm). Usage speed doesn't suffer though, it just takes forever
to build the first time or when replacing a disk.


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