0

My question is for a low cost home workstation, in a hard to replace hardware situation.

So what is the best practice using LVM? and without raid.

1) I think I should create logical volumes restricted to physical volumes (so if one of my 3 HDs that seem ready to fail, will not compromise the data on others). is that true?

2) Also I intend to create a single lvm group thru all HDs, and leave some space unallocated by any logical volume on them all, so I can create snapshots on them.

But I am still finding it hard to dethermine thru research:

  • What will happen if any HD that is on that single lvm group, storing only the main logical volume snapshots, fail?
  • Will my machine stop booting as there is a missing group member?
  • To boot is only required that the full logical volume is available?

I am still confused about the risks and I still cannot find similar question that answers what I need.

Obs.: I am using KVPM to make several tests (on linux), merging groups, extending LV (on a single physical volume) etc. And I still have to unplug one of the group members to see what happens (making it sure any LV is limited to a single PV)

thanks on tips too!

PS.: I will try to phrase it better as I understand it better later

1 Answer 1

1

I think I should create logical volumes restricted to physical volumes (so if one of my 3 HDs that seem ready to fail, will not compromise the data on others).

You can create mirrors of your logical volumes ('lvcreate -m1 ...') so that if one disk dies your data will still exist on another disk, without any data loss.

Will my machine stop booting as there is a missing group member?

If the missing disk contains /, /boot or the boot sectors, then yes. Missing volumes will obviously fail to mount.

I keep a bootable CD of System Rescue CD nearby.

5
  • so instead of a snapshot, it would be better to create a mirror of my /? any idea about the differences? going to check now too. Also, the possibly missing disk will not have any part of the main volume at /, so, as I understand, missing group members do not interfere on mounting logical volumes (that are not spread into these missing physical volumes), cool! Feb 21, 2015 at 1:34
  • 1
    A mirror will protect you against device failure, but will do nothing against "oops, I didn't mean to delete that". Snapshots are good for going back in time.
    – pgs
    Feb 21, 2015 at 1:38
  • I just tested, unplugging one PV (that has no LV part, just mirrors or snapshots) keeps the other LVs on the group actively working; but... the LV with a mirror leg on it, became inaccessible; may be kvpm cant handle it, still testing. Feb 21, 2015 at 2:09
  • kvpm "remove missing physical volumes" did the trick, I recovered access to the mirrored volume! I think it is all good now, thanks! Feb 21, 2015 at 2:45
  • linking what I believe is the recover coomandline: serverfault.com/a/534283/163750, pvdisplay;vgreduce --removemissing --force $vgname Feb 22, 2015 at 0:33

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .