[ClusterLabs] snapshots in a clvm environment - some questions for proceeding

Lentes, Bernd bernd.lentes at helmholtz-muenchen.de
Fri Feb 24 13:00:39 EST 2017

----- On Feb 24, 2017, at 6:24 PM, Bernd Lentes bernd.lentes at helmholtz-muenchen.de wrote:

> Hi,
> we have a two node cluster, our resources are several virtual machines running
> on kvm. The vm's reside in plain logical volumes, without a filesystem inside
> the lv's.
> The lv's reside on a SAN.
> I know that i can do a snapshot of a lv while having clvm when i acitivate it
> exclusively on one node. OK.
> I tried it via lvchange -aly. I got "lvchange Using logical volume(s) on command
> line. lvchange    Activating logical volume "lv_cluster_01" locally". Seems to
> work.
> Then i'm able to take the snapshot. But what is when i'd like to activate the lv
> cluster-wide again ? Is the snapshot gone or corrupted ?
> I tried to activate it cluster-wide again with "lvchange -vay". Seems to work
> too.
> Because, if i leave it exclusively activated on one note, i loose my high
> availibilty. How can it migrate to the other host if it is exclusively
> activated ?
> How can i find out if a lv is activated exclusively ? How can i find out on
> which node it is activated exclusively ?
> Thanks.

I read https://www.centos.org/docs/5/html/Cluster_Logical_Volume_Manager/cluster_activation.html .
It seems that a local activation is not an exclusiv one. Ok. I tried "lvchange -vaey" for that lv, but got:
lvchange    Using logical volume(s) on command line
lvchange    Activating logical volume "lv_cluster_01" exclusively
lvchange  Error locking on node 40a86414: Device or resource busy

I shut down the guest, still the same message.


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