[linux-lvm] enclosure separation/turnoff

[Patrick Caulfield]

On Tue, Feb 11, 2003 at 05:51:23PM -0500, Alexy Khrabrov wrote:
> 
> I would like to see what would be a good way to use LVM
> with a bunch of external SCSI enclosures ("boxes").  I have
> several of these, with the number of drives ranging
> from 1 to 2 to 4 per each.  First I created a logical volume
> per each box, but then realized the sizes were not exactly
> matched, and now I get thrashing when trying to move stuff
> from one enclosure box to another.  So the first question
> is, (1) how does one create a logical volume exactly corresponding 
> to an external box (a set of drives)? (2) Is it a good idea
> to stripe an external box, given that data moves occur primarily
> between the boxes, not within each?  Then I'd stripe each
> box with the number of stripes being the number of drives in it.
> (3) Is there a way to resize the logical volumes so they are 
> remapped to their enclosures exactly, without reloading the
> contents?  (4) To make sure my latest box is done right, I created
> a new volume group for it.  Is this a good use for multiple
> volume groups (other than the usual lone "system")?
> 
> Now, I wanted to temporarily turn off the external enclosures
> as I didn't need their contents.  However, Linux would not boot
> properly!  Even when I disable the boxes in /etc/fstab,
> it fails to boot; even when I deactivate the logical volumes
> corresponding to the boxes with lvchange -a n <path>
> for each, and deactivate the last box with vgchange -a n <group>,
> failure on boot -- can't find many standard paths!  Looks
> like vgscan thinks something is still there and I get a message
> "spinning sdd", while sdd is in one of the deactivated LVs,
> and I'm forced to power on all of the boxes even while none
> is mounted nor used.  (5) How do I achieve clean separation so
> that I can shut down any or all external enclosures easily?

It sounds like you really just want to use each disk with a single
partition on it. LVM in this instance is not going to buy you anything.

-- 

patrick