[svlug] Projecting two disks as one

Karen Shaeffer shaeffer at neuralscape.com
Tue Jul 19 10:30:48 PDT 2005

On Mon, Jul 18, 2005 at 11:20:39PM -0700, Karsten M. Self wrote:
> on Tue, Jul 19, 2005 at 12:04:32AM -0400, David Hummel (dhml at comcast.net) wrote:
> > On Mon, Jul 18, 2005 at 08:49:48PM -0700, Rufoo wrote:
> > > 
> > > I am running out of space on a disk and I am planning to add another
> > > one. Is it possible to project the second one as part of a
> > > partition(ext3) in the first one? In other words, can a partition span
> > > multiple physical harddrives?
> > 
> >   http://sources.redhat.com/lvm2/
> ...though this will require wiping and rebuilding both disks as part of
> the LVM.  Still, when it works, pretty slick.

Hello Rufoo,

If you have a default install of a recent Redhat distribution, then you
already have lvm2. In any event, you should first make sure you are
running the latest lvm2, device-mapper, and linux kernel possible for
your circumstances. Then back up your filesystem for safety.

You can add the new disk or a portion of it, as a new physical
volume, incorporating it into the lvm. Then you can add this new physical
volume to the volume group that the original disk is part of. Then you can
grow the logical volume. Then you can grow the filesystem. You do not have
to wipe it clean. (Always back it up before doing this -- if you want to
ensure nothing goes wrong.)

If you are not currently running in lvm2, then, you can start using it
with the new disk. Once it is online, then you can just copy the original
disk over to this new one. Then wipe the old one clean. Then add the old
one to the lvm and proceed as normal to add space to the logical volume,
and finally growing the filesystem.

 Karen Shaeffer
 Neuralscape, Palo Alto, Ca. 94306
 shaeffer at neuralscape.com  http://www.neuralscape.com

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