Tuesday, July 19, 2011

LVM: How to remove a volume using pvremove

First, I encountered this error "Can't pvremove physical volume "/dev/sdc1" of volume group "nova-volumes" without -ff" (I'm actually using OpenStack but it's another story).

So to remove this, do first,

~# pvscan
  PV /dev/sdb1   VG nova-volumes    lvm2 [1.82 TiB / 1.82 TiB free]
  PV /dev/sda5   VG cloudmaster     lvm2 [297.85 GiB / 12.00 MiB free]
  PV /dev/sdc1                      lvm2 [1.82 TiB]
  Total: 3 [3.93 TiB] / in use: 2 [2.11 TiB] / in no VG: 1 [1.82 TiB]

Then, when I do,

~# pvremove /dev/sdc1
 Can't pvremove physical volume "/dev/sdc1" of volume group "nova-volumes" without -ff

So I need to,

~# vgreduce nova-volumes /dev/sdc1
  Removed "/dev/sdc1" from volume group "nova-volumes"


Then do `pvscan` again,

~# pvscan
  PV /dev/sdb1   VG nova-volumes    lvm2 [1.82 TiB / 1.82 TiB free]
  PV /dev/sda5   VG cloudmaster     lvm2 [297.85 GiB / 12.00 MiB free]
  PV /dev/sdc1                      lvm2 [1.82 TiB]
  Total: 3 [3.93 TiB] / in use: 2 [2.11 TiB] / in no VG: 1 [1.82 TiB]

Then now, I can remove this by,

~# pvremove /dev/sdc1
  Labels on physical volume "/dev/sdc1" successfully wiped



Then running `pvscan` again,

root@cloudmaster:~# pvscan
  PV /dev/sdb1   VG nova-volumes   lvm2 [1.82 TiB / 1.82 TiB free]
  PV /dev/sda5   VG cloudmaster    lvm2 [297.85 GiB / 12.00 MiB free]
  Total: 2 [2.11 TiB] / in use: 2 [2.11 TiB] / in no VG: 0 [0   ]


Shows that the /dev/sdc device is now removed. Hope this helps.


1 comment:

KenP said...

Hi, I have a peculiar problem, probably due to my own negligence (as most often.)

I have an external HDD which when connected to my laptop is now showing as LVM2_member. It did not auto-mount so I opened a terminal to take a look. On trying to mount it from the command line, it showed unknown filesystem type 'LVM2_member'.

Now, when I use fdisk to look at the disk, it shows one partition with HPFS/NTFS/exFAT as the type, which I presume is Windows fs format.

My questions:
1. Is my hard-disk bricked i.e. have I lost all data?
2. In the happy condition that answer to 1. is "no", can I recover the data?

I am contemplating using pvremove on the disk. Will that wipe the data too? Just want to check before I do anything more stupid now.

Btw, pvs shows the partition on the external HDD as a physical volume, but is not assigned to any vg.

Thanks!