[ClusterLabs] [pacemaker+ clvm] Cluster lvm must be active exclusively to create snapshot

su liu liusu8788 at gmail.com
Mon Dec 5 21:10:44 EST 2016


Thanks for your replay,  This snapshot factor will seriously affect my
application.

then, because now I have not a stonith device and I want to verify the
basic process of snapshot a clustered LV.

I have a more question:

After I create a VG: cinder-volumes on controller node, I can see it
throuth vgs command on both controller and compute
1 nodes. then i create a LV:volume-1b0ea468-37c8-4b47-a6fa-6cce65b068b5.
Then I execute the lvs command on both nodes:

[root at controller ~]# lvs
  LV                                          VG             Attr
LSize Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  volume-1b0ea468-37c8-4b47-a6fa-6cce65b068b5 cinder-volumes -wi-a-----
1.00g
[root at controller ~]#
[root at controller ~]#
[root at controller ~]#
[root at controller ~]# ll /dev/cinder-volumes/
total 0
lrwxrwxrwx 1 root root 7 Dec  5 21:29
volume-1b0ea468-37c8-4b47-a6fa-6cce65b068b5 -> ../dm-0



[root at compute1 ~]# lvs
  LV                                          VG             Attr
LSize Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  volume-1b0ea468-37c8-4b47-a6fa-6cce65b068b5 cinder-volumes -wi-------
1.00g
[root at compute1 ~]#
[root at compute1 ~]#
[root at compute1 ~]# ll /dev/cinder-volumes
ls: cannot access /dev/cinder-volumes: No such file or directory
[root at compute1 ~]#



But it seems that the LV can't be exist on the compute1 node. My question
is that how to access the LV on the compute1 node?

thanks very much!

2016-12-06 9:26 GMT+08:00 Digimer <lists at alteeve.ca>:

> On 05/12/16 08:16 PM, su liu wrote:
> > *Hi all,
> >
> > *
> > *I am new to pacemaker and I have some questions about the clvmd +
> > pacemaker + corosync. I wish you could explain it for me if you are
> > free. thank you very much!
> >
> > *
> > *I have 2 nodes and the pacemaker's status is as follows:*
> >
> > [root at controller ~]# pcs status --full
> > Cluster name: mycluster
> > Last updated: Mon Dec  5 18:15:12 2016        Last change: Fri Dec  2
> > 15:01:03 2016 by root via cibadmin on compute1
> > Stack: corosync
> > Current DC: compute1 (2) (version 1.1.13-10.el7_2.4-44eb2dd) - partition
> > with quorum
> > 2 nodes and 4 resources configured
> >
> > Online: [ compute1 (2) controller (1) ]
> >
> > Full list of resources:
> >
> >  Clone Set: dlm-clone [dlm]
> >      dlm    (ocf::pacemaker:controld):    Started compute1
> >      dlm    (ocf::pacemaker:controld):    Started controller
> >      Started: [ compute1 controller ]
> >  Clone Set: clvmd-clone [clvmd]
> >      clvmd    (ocf::heartbeat:clvm):    Started compute1
> >      clvmd    (ocf::heartbeat:clvm):    Started controller
> >      Started: [ compute1 controller ]
> >
> > Node Attributes:
> > * Node compute1 (2):
> > * Node controller (1):
> >
> > Migration Summary:
> > * Node compute1 (2):
> > * Node controller (1):
> >
> > PCSD Status:
> >   controller: Online
> >   compute1: Online
> >
> > Daemon Status:
> >   corosync: active/disabled
> >   pacemaker: active/disabled
> >   pcsd: active/enabled
> > *
> > *
>
> You need to configure and enable (and test!) stonith. This is doubly-so
> with clustered LVM/shared storage.
>
> > *I create a lvm on controller node and it can be seen on the compute1
> > node immediately with 'lvs' command. but the lvm it not activate on
> > compute1.
> >
> > *
> > *then i want to create a snapshot of the lvm, but failed with the error
> > message:*
> >
> > /### volume-4fad87bb-3d4c-4a96-bef1-8799980050d1 must be active
> > exclusively to create snapshot ###
> >
> > /
> > *Can someone tell me how to snapshot a lvm in the cluster lvm
> > environment? thank you very much。*
>
> This is how it works. You can't snapshot a clustered LV, as the error
> indicates. The process is ACTIVE -> deactivate on all node -> set
> exclusive on one node -> set it back to ACTIVE, then you can snapshot.
>
> It's not very practical, unfortunately.
>
> > Additional information:
> >
> > [root at controller ~]# vgdisplay
> >   --- Volume group ---
> >   VG Name               cinder-volumes
> >   System ID
> >   Format                lvm2
> >   Metadata Areas        1
> >   Metadata Sequence No  19
> >   VG Access             read/write
> >   VG Status             resizable
> >   Clustered             yes
> >   Shared                no
> >   MAX LV                0
> >   Cur LV                1
> >   Open LV               0
> >   Max PV                0
> >   Cur PV                1
> >   Act PV                1
> >   VG Size               1000.00 GiB
> >   PE Size               4.00 MiB
> >   Total PE              255999
> >   Alloc PE / Size       256 / 1.00 GiB
> >   Free  PE / Size       255743 / 999.00 GiB
> >   VG UUID               aLamHi-mMcI-2NsC-Spjm-QWZr-MzHx-pPYSTt
> >
> > [root at controller ~]# rpm -qa |grep pacem
> > pacemaker-cli-1.1.13-10.el7_2.4.x86_64
> > pacemaker-libs-1.1.13-10.el7_2.4.x86_64
> > pacemaker-1.1.13-10.el7_2.4.x86_64
> > pacemaker-cluster-libs-1.1.13-10.el7_2.4.x86_64
> >
> >
> > [root at controller ~]# lvs
> >   LV                                          VG             Attr
> > LSize Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
> >   volume-1b0ea468-37c8-4b47-a6fa-6cce65b068b5 cinder-volumes -wi-a-----
> > 1.00g
> >
> >
> > [root at compute1 ~]# lvs
> >   LV                                          VG             Attr
> > LSize Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
> >   volume-1b0ea468-37c8-4b47-a6fa-6cce65b068b5 cinder-volumes -wi-------
> > 1.00g
> >
> >
> > thank you very much!
> >
> >
> >
> >
> >
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>
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