[linux-lvm] Removing a PV

[Rob Foehl]

Ok, that's kind of what I was expecting..

The drive being removed is going to get wiped anyway, I'm not trying to
move any data with it, I just need space in another system and we're well
below capacity on the current one.. The only thing I want to keep intact
is the data on the existing filesystem.

Thanks for the info.. I'll give it a try in the morning.

On Mon, 13 Nov 2000, Andreas Dilger wrote:

> Rob Foehl writes:
> > I'd assumed that was the correct command sequence, but does lvreduce
> > ensure that the filesystem won't be damaged? Ie. does it only remove LE's
> > from the end of the LV, or what?
> 
> Yes, the LEs are logically numbered, so they are always added to and removed
> from the end of the device.  That makes it much easier on the filesystem
> because it doesn't need to ever deal with the blocks at the start of the
> filesystem changing.  However, since they are "logical" blocks, they
> can be physically moved between disks without affecting the filesystem.
> 
> As for removing a disk with a filesystem from an existing VG - you have
> to realize that there is still LVM information at the start of the disk
> even if you remove it from the VG, so you will not be able to use it as-is
> on another system.
> 
> Rather than doing an lvreduce/pvmove/vgreduce (as previously suggested),
> you should do a pvmove to move all of the LEs from the desired filesystem
> into a single PV (it may already be this way) and also move all of the
> undesired LEs from this PV onto other PVs in the VG (use pvdisplay -v and
> lvdisplay -v to find out the layout).  Then use vgsplit to create two
> new VGs - the new one being the single filesystem/disk you want to move.
> You can then export the VG from the current system and import it to the
> new system.
> 
> If you are not going to use LVM on the new system, then simply pvmove all
> of the LEs from one of your disks and vgreduce this PV from the VG.  Then
> use fdisk to make a new partition on the disk, and dd to copy from the
> old LV to the new partition.  This way you will also have a backup of the
> data should anything go wrong (which you should probably have on tape as
> well).
> 
> Cheers, Andreas
> 
> 
> > On Mon, 13 Nov 2000, Luca Berra wrote:
> > 
> > > On Mon, Nov 13, 2000 at 01:12:23PM -0500, Rob Foehl wrote:
> > > > If I want to completely pull a drive that belongs to a VG with an ext2
> > > > formatted LV in it, what's the correct procedure to avoid mangling the
> > > > filesystem? I currently have a 130 gig partition spread over six
> > > > drives.. about 74 gigs is in use, and I wanted to remove a single 20 gig
> > > > drive from the volume.. I'm assuming I should shrink the filesystem by
> > > > around 30 gigs or so (to be safe), then somehow also shrink the LV and
> > > > move any used PEs on the 20 gig drive in question onto freed space on
> > > > other drives.. Any suggestions would be greatly appreciated.
> > > 
> > > ext2resize/resize2fs
> > > lvreduce
> > > pvmove
> > > vgreduce
> > > 
> > > 
> > > -- 
> > > Luca Berra -- bluca at comedia.it
> > >     Communication Media & Services S.r.l.
> > > 
> > 
> > 
> 
> 
> -- 
> Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
>                  \  would they cancel out, leaving him still hungry?"
> http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert
>