Skip to contentSkip to conversation

Question re: deleting an LV...

linux-lvm Tanstaafl 3 participants 5 messages Dec 30, 2013 – Jan 6, 2014

lore
Share & tools
lore

Tanstaafl

author
#0 lore raw

Hello,

Due to a misunderstanding about how LVM snapshots work when I set up this system, I now need to delete an LV I had created to use for this purpose (I thought I had to pre-create the LV).

Currently I have:

 # lvscan
  ACTIVE            '/dev/vg/tmp' [5.00 GiB] inherit
  ACTIVE            '/dev/vg/log' [5.00 GiB] inherit
  ACTIVE            '/dev/vg/vtmp' [5.00 GiB] inherit
  ACTIVE            '/dev/vg/var' [700.00 GiB] inherit
  ACTIVE            '/dev/vg/snaps' [4.00 GiB] inherit

I just need to delete the /dev/vg/snaps LV, so that that 4GB is available for my LVM snapshots.

Am I correct that all I have to do is:

# umount /dev/vg/snaps
# lvremove /dev/vg/snaps

Then remove this line from fstab?

This would then result in my VG having 4GB available for taking LVM snapshots?

Thanks

author
#1 lore raw
Quoted 20 lines · Tanstaafl

Hello,

Due to a misunderstanding about how LVM snapshots work when I set up this system, I now need to delete an LV I had created to use for this purpose (I thought I had to pre-create the LV).

Currently I have:

  # lvscan
   ACTIVE            '/dev/vg/tmp' [5.00 GiB] inherit
   ACTIVE            '/dev/vg/log' [5.00 GiB] inherit
   ACTIVE            '/dev/vg/vtmp' [5.00 GiB] inherit
   ACTIVE            '/dev/vg/var' [700.00 GiB] inherit
   ACTIVE            '/dev/vg/snaps' [4.00 GiB] inherit

I just need to delete the /dev/vg/snaps LV, so that that 4GB is available for my LVM snapshots.

Am I correct that all I have to do is:

Quoted 7 lines
# umount /dev/vg/snaps
# lvremove /dev/vg/snaps

Then remove this line from fstab?

This would then result in my VG having 4GB available for taking LVM snapshots?

Would appreciate a confirmation that I don't have to do anything else to totally eliminate the snaps LV...

I unmounted it, and commented that line in fstab. lvscan still shows the same as above, but lvs shows the snaps with a slightly different attribute:

 # lvs
  LV    VG   Attr       LSize
  log   vg   -wi-ao----   5.00g
  snaps vg   -wi-a-----   4.00g
  tmp   vg   -wi-ao----   5.00g
  var   vg   -wi-ao---- 700.00g
  vtmp  vg   -wi-ao----   5.00g

So again - is lvremove /dev/vg/snaps the correct way - and the only thing I need to do - to remove that LV as if it had never been created?

Thanks

#2 lore raw
Quoted 43 lines · Tanstaafl
Quoted 20 lines · Tanstaafl

Hello,

Due to a misunderstanding about how LVM snapshots work when I set up this system, I now need to delete an LV I had created to use for this purpose (I thought I had to pre-create the LV).

Currently I have:

  # lvscan
   ACTIVE            '/dev/vg/tmp' [5.00 GiB] inherit
   ACTIVE            '/dev/vg/log' [5.00 GiB] inherit
   ACTIVE            '/dev/vg/vtmp' [5.00 GiB] inherit
   ACTIVE            '/dev/vg/var' [700.00 GiB] inherit
   ACTIVE            '/dev/vg/snaps' [4.00 GiB] inherit

I just need to delete the /dev/vg/snaps LV, so that that 4GB is available for my LVM snapshots.

Am I correct that all I have to do is:

Quoted 7 lines
# umount /dev/vg/snaps
# lvremove /dev/vg/snaps

Then remove this line from fstab?

This would then result in my VG having 4GB available for taking LVM snapshots?

Would appreciate a confirmation that I don't have to do anything else to totally eliminate the snaps LV...

I unmounted it, and commented that line in fstab. lvscan still shows the same as above, but lvs shows the snaps with a slightly different attribute:

  # lvs
   LV    VG   Attr       LSize
   log   vg   -wi-ao----   5.00g
   snaps vg   -wi-a-----   4.00g
   tmp   vg   -wi-ao----   5.00g
   var   vg   -wi-ao---- 700.00g
   vtmp  vg   -wi-ao----   5.00g
Quoted 2 lines

So again - is lvremove /dev/vg/snaps the correct way - and the only thing I need to do - to remove that LV as if it had never been created?

Yes. This page has a definition of the attributes: http://man7.org/linux/man-pages/man8/lvs.8.html. "o" in position 6 means device open; since you've unmounted it, it is no longer open.

I learned via this mailing list that lvremove just updates metadata to make the space available again, but doesn't remove the filesystem in the LV. So if you were to recreate the exact same LV you just removed, the filesystem would still be there. My situation was unusual, and you probably won't encounter this. But if you want to avoid that minor possibility, use "wipefs -a /dev/vg/snaps" before lvremove.

Signature · 5 lines
Guy Rouillier

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com
author
#3 lore raw
Quoted 6 lines · Guy Rouillier

I learned via this mailing list that lvremove just updates metadata to make the space available again, but doesn't remove the filesystem in the LV. So if you were to recreate the exact same LV you just removed, the filesystem would still be there. My situation was unusual, and you probably won't encounter this. But if you want to avoid that minor possibility, use "wipefs -a /dev/vg/snaps" before lvremove.

Thanks for the reply Guy...

I don't think this is necessary, as this space

a) never had anything written to it, and

b) will be used for LVM snapshots, so even if it had, it would get overwritten very soon.

Anyway, thanks... looking forward to getting my email rsnapshot backups working using LVM snapshots (for consistency - no more 'file vanished' messages during backups)...

Thx again

Charles

#4 lore raw
In reply to Guy Rouillier
Quoted 56 lines · Guy Rouillier
Quoted 47 lines · Tanstaafl
Quoted 21 lines · Tanstaafl

Hello,

Due to a misunderstanding about how LVM snapshots work when I set up this system, I now need to delete an LV I had created to use for this purpose (I thought I had to pre-create the LV).

Currently I have:

  # lvscan
   ACTIVE            '/dev/vg/tmp' [5.00 GiB] inherit
   ACTIVE            '/dev/vg/log' [5.00 GiB] inherit
   ACTIVE            '/dev/vg/vtmp' [5.00 GiB] inherit
   ACTIVE            '/dev/vg/var' [700.00 GiB] inherit
   ACTIVE            '/dev/vg/snaps' [4.00 GiB] inherit

I just need to delete the /dev/vg/snaps LV, so that that 4GB is available for my LVM snapshots.

Am I correct that all I have to do is:

Quoted 7 lines
# umount /dev/vg/snaps
# lvremove /dev/vg/snaps

Then remove this line from fstab?

This would then result in my VG having 4GB available for taking LVM snapshots?

Would appreciate a confirmation that I don't have to do anything else to totally eliminate the snaps LV...

I unmounted it, and commented that line in fstab. lvscan still shows the same as above, but lvs shows the snaps with a slightly different attribute:

  # lvs
   LV    VG   Attr       LSize
   log   vg   -wi-ao----   5.00g
   snaps vg   -wi-a-----   4.00g
   tmp   vg   -wi-ao----   5.00g
   var   vg   -wi-ao---- 700.00g
   vtmp  vg   -wi-ao----   5.00g
Quoted 2 lines

So again - is lvremove /dev/vg/snaps the correct way - and the only thing I need to do - to remove that LV as if it had never been created?

Yes. This page has a definition of the attributes:
http://man7.org/linux/man-pages/man8/lvs.8.html. "o" in position 6 means device open; since you've unmounted it, it is no longer open.

Quoted 7 lines

I learned via this mailing list that lvremove just updates metadata to make the space available again, but doesn't remove the filesystem in the LV. So if you were to recreate the exact same LV you just removed, the filesystem would still be there. My situation was unusual, and you probably won't encounter this. But if you want to avoid that minor possibility, use "wipefs -a /dev/vg/snaps" before lvremove.

Going a bit on a tangent, thanks for the info. I need to add
that to my notes because sometimes when I want a lv to go away, I really really want it to go

Quoted 14 lines

--
Guy Rouillier

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

_______________________________________________
linux-lvm mailing list
[email protected]
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/