Hi!

This issue can be replicated by the following steps:
1. setup two-node HA cluster with dlm and clvmd RAs configured;
2. prepare a shared disk through iscsi, named "sdb" for example;

3. execute lvm cmds on n1:
lvm2dev1:~# pvcreate /dev/sdb
Physical volume "/dev/sdb" successfully created
lvm2dev1:~ # vgcreate vg1 /dev/sdb
    Clustered volume group "vg1" successfully created
lvm2dev1:~ # lvcreate -l100%VG -n lv1 vg1
    Logical volume "lv1" created.
lvm2dev1:~ # lvchange -an vg1/lv1

4. disconnect shared iscsi disk on n2;
5. to activate vg1/lv1 on n1:
lvm2dev1:~ # lvchange -ay vg1/lv1
Error locking on node UNKNOWN 1084783200: Volume group for uuid not found: TG0VguoR1HxSO1OPA0nk737FJSQTLYAMKV2M20cfttItrRnJetTZmKxtKs3a88Ri

6. re-connect shared disk on n2;
7. execute `clvmd -R` on n1; and then I can activate lv1 successfully.

In local mode, lvm will make a full scan on disks each time when lvmetad is 
disable. As we know,
lvmetad is also disable when clvm is in use, so that device cache can not be refreshed automatically
when device is added or removed. We can solve this issue by executing "clvmd 
-R" manually. But,
in some auto scripts, it's boring to put "clvmd -R" before some lvm commands 
everywhere.

So, is there an option to enable full scan every time when lvm is invoked in 
cluster scenario?
Thanks in advance:)

Regards,
Eric

On 04/14/2017 06:27 PM, Eric Ren wrote:
Hi!

In cluster environment, lvcreate/lvchange may fail to activate logical volumes 
sometimes.

For example:

# lvcreate -l100%VG -n lv001 clustermd
Error locking on node a52cbcb: Volume group for uuid not found: SPxo6WiQhEJWDFyeul4gKYX2bNDVEsoXRNfU3fI5TI9Pd3OrIEuIm8jGtElDJzEy
   Failed to activate new LV.

The log file for this failure is attached. My thoughts on this issue follows, for example on two nodes:
n1:
===
#lvchange -ay vg/lv1
...
clvmd will ask for peer daemon on n2
to activate lv1 as well

n2:
===
lvm need to find lv1 and the PVs for lv1,
in device cache which aims to avoid frequent scan all
disks. But if the PV(s) might not be available
in device cache, it responses n1 with errors....

We found that 'clvmd -R' can be a workaround before activating LV, because
what "clvmd -R" is to refresh device cache on every node as its commit message 
said:
===
commit 13583874fcbdf1e63239ff943247bf5a21c87862
Author: Patrick Caulfield <pcaul...@redhat.com>
Date:   Wed Oct 4 08:22:16 2006 +0000

     Add -R switch to clvmd.
This option will instruct all the clvmd daemons in the cluster to reload their device cache
==

I think the reason why clvm doesn't refresh device cache every time before 
activating LV,
is to avoid scanning all disks frequently.

But, I'm not sure if I understand this issue correctly, will appreciate much if 
someone can
help.

Regards,
Eric




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