[linux-lvm] clvm: failed to activate logical volumes sometimes

[Eric Ren]

Hi!
On 04/20/2017 04:29 PM, emmanuel segura wrote:
> maybe you are using an old clvm version, I rember that in the new
> version you don't need to execute any command on the secondary node.
Thanks for your reply! Yes, I don't need to execute any command on any
remote node. But, in such case, we need "clvmd -R" on one of the nodes.

BTW, my versions:
lvm2-clvm-2.02.120-72.8.x86_64
lvm2-2.02.120-72.8.x86_64

Regards,
Eric
>
> 2017-04-20 10:06 GMT+02:00 Eric Ren <zren at suse.com>:
>> 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 <pcaulfie at 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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>>> linux-lvm at redhat.com
>>> https://www.redhat.com/mailman/listinfo/linux-lvm
>>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>
>>
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>
>