[linux-lvm] Expanding a PV on a hardware RAID

Jetkins at austinlogistics.com Jetkins at austinlogistics.com
Mon Nov 15 18:47:28 UTC 2004

Hi, folks.

I think I may have painted myself into a corner, but I thought I'd ask here
before I undo what I've done so far.  My configuration is as follows:

I have a hardware RAID with 2 logical drives defined.  The second logical
drive (/dev/sdb) is dedicated entirely to LVM.  When I set up LVM, I used
      pvcreate /dev/sdb
to allocate the entire logical drive, rather than creating a partition
table and using
      pvcreate /dev/sdb1

I then created a VG with just the single PV, and several LV's.  It's all
working great, but I need to expand the available capacity.

Thinking this would be a simple operation, I added three new drives to the
RAID5 array, taking the available space from ~850GB to ~1.25TB.  The RAID
controller dynamically expanded /dev/sdb to the new size, which the OS
recognized after a reboot:

      SCSI device sdb: 2578636800 512-byte hdwr sectors (1320262 MB)
       sdb: unknown partition table

I thought I would simply be able to expand the PV to take up the newly
available space on the "new larger disk".  However, I can't seem to find
any way to expand a PV, and therein lies my problem.  It seems that without
a pvexpand or pvresize command, I have no way of utilizing the additional

Without that ability, it seems that I have no alternative but to remove the
additional drives (taking /dev/sdb back to its original size), create a new
RAID5 array (/dev/sdc), and create a new PV on that logical drive.  Total
bummer because I lose another 147GB drive to parity for the new array, but
I don't see any other way out.

So my questions are twofold:

1)  Am I missing something, or is there currently no way to expand a PV?,

2)  Would I have been better off creating a partition table and
pvcreate'ing on /dev/sdb1instead of pvcreate'ing the entire /dev/sdb disk
initially, given that I could now have created a new partition on the extra
space and pvreate'd a new PV alongside the old?

Thanks in advance,

Jon Etkins
IT Administration & Support
Austin Logistics, Inc
ph:  (512) 651-5641
fax: (512) 329-5625

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