[ClusterLabs] Antw: Re: Antw: [EXT] Re: Q: What is lvmlockd locking?

[Roger Zhou]

On 1/22/21 4:17 PM, Ulrich Windl wrote:
>>>> Gang He<ghe at suse.com>  schrieb am 22.01.2021 um 09:13 in Nachricht
> <1fd1c07d-d12c-fea9-4b17-90a977fe783b at suse.com>:
>> Hi Ulrich,
>>
>> I reviewed the crm configuration file, there are some comments as below,
>> 1) lvmlockd resource is used for shared VG, if you do not plan to add
>> any shared VG in your cluster, I suggest to drop this resource and clone.

Agree with Gang.

No need 'lvmlockd' in your configuration anymore. You could remove all 
"lvmlocked" related configuration.

>> 2) second, lvmlockd service depends on DLM service, it will create
>> "lvm_xxx" related lock spaces when any shared VG is created/activated.
>> but some other resource also depends on DLM to create lock spaces for
>> avoiding race condition, e.g. clustered MD, ocfs2, etc. Then, the file
>> system resource should start later than lvm2(lvmlockd) related resources.
>> That means this order should be wrong.
>> order ord_lockspace_fs__lvmlockd Mandatory: cln_lockspace_ocfs2 cln_lvmlock
> But cln_lockspace_ocfs2 provides the shared filesystem that lvmlockd uses. I
> thought for locking in a cluster it needs a cluster-wide filesystem.
> 

I understand your root motivation is to setup virtlockd on top of ocfs2.

There is no relation between ocfs2 and lvmlockd unless you setup ocfs2 on top 
of Cluster LVM(aka. shared VG) which is not your case.

Could be the naming of lvmlockd and virtlockd mislead you, I guess.

Anyway, two more tweaks needed in your CIB:

colocation col_vm__virtlockd inf: ( prm_xen_test-jeos1 prm_xen_test-jeos2 
prm_xen_test-jeos3 prm_xen_test-jeos4 ) cln_lockspace_ocfs2

order ord_virtlockd__vm Mandatory: cln_lockspace_ocfs2 ( prm_xen_test-jeos1 
prm_xen_test-jeos2 prm_xen_test-jeos3 prm_xen_test-jeos4 )


BR,
Roger