[CentOS] Add more space to LVM

Thu Jan 17 19:19:13 UTC 2008
Ross S. W. Walker <rwalker at medallion.com>

John R Pierce wrote:
> 
> Tim Verhoeven wrote:
> > This is perfectly possible with LVM. First add the HD (aka 
> the HW RAID
> > volume) to the OS. Then do a pvcreate on that disk so that 
> LVM can use
> > it. Then do a vgextend, this adds the disk to the volume group. A
> > vgdisplay should then show that you have again free space in the
> > volume group. Then you can do a lvextend and resize2fs as normal.
> >   
> 
> 
> and, get it all -exactly- right, or its krispy kritters for your FS.

May I also add that one should be aware of what type of physical
volumes your data is contained on too.

If your original data is on a software RAID array consisting of
internal drives, say /dev/md3, and you add an external enclosure
which is under hardware raid, say /dev/sde, you may want to just
move your data off the software RAID PV onto the hardware RAID
PV and remove the software RAID PV from the VG so you can rest
easy knowing that ALL of your data is on the managed hardware
RAID array and not split 60/40 between them. (Or keep the software
RAID array in the VG for volume snapshots only).

To do this I would do a pvmove of all data on /dev/md3 to /dev/sde
first, then remove /dev/md3 from the VG, pvremove /dev/md3 and
then lvextend your LV further on to PV /dev/sde.

Later if you add an addition storage enclosure on to the hardware
RAID I would still think about keeping separate LVs completely
on separate enclosures and pvmove LVs from one PV to another to
free up space before lvextending.

I always tell lvextend and lvcreate exactly which PVs to use
on the command line.

-Ross

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