[linux-lvm] auto umount at thin meta 80%

Zdenek Kabelac zkabelac at redhat.com
Mon May 23 08:40:09 UTC 2016


On 22.5.2016 19:07, Xen wrote:
> I am not sure if, due to my recent posts ;-) I would still be allowed to write
> here. But, perhaps it is important regardless.
>
> I have an embedded LVM. The outer volume is a cached LVM, that is to say, two
> volumes are cached from a different PV. One of the cached volumes contains LUKS.
>
> The LUKS, when opened, contains another PV, VG, and a thin pool.
>
> The thin pool contains about 4-5 partitions and is overprovisioned. Only one
> volume is in use now.
>
> This thin volume called "Store" is almost the full size of the thin pool, but
> not quite:
>
> store    vault Vwi-aotz-- 400.00g thin                        40.37
>
> It currently stores a backup, I was writing some backup scripts.
>
> The volume apparently got umounted when the meta of the thinpool reached 80%.
>
> 10:47:21 lvm[4657]: WARNING: Thin pool vault-thin-tpool metadata is now 80.14%
> full.
> 10:47:21 lvm[4657]: Request to lookup VG vault in lvmetad gave response
> Connection reset by peer.
> 10:47:21 lvm[4657]: Volume group "vault" not found
> 10:47:21 lvm[4657]: Failed to extend thin pool vault-thin-tpool.

At this moment -   any failure in  'lvresize' execution leads to immediate 
umount - tool went ballistic and so takes 'drastic' action to prevent further
damage.

See here again:

https://www.redhat.com/archives/linux-lvm/2016-May/msg00064.html

ATM there is some new code which unconditionally always connects to lvmetad
even it's not necessary at all - and it's potential source of many other
troubles - so fixes here are in progress  -   set 'use_lvmetad=0'  if it's 
still a problem in your case.

Regards

Zdenek




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