[ClusterLabs] Any CLVM/DLM users around?

Vladislav Bogdanov bubble at hoster-ok.com
Mon Oct 1 14:14:30 EDT 2018

On October 1, 2018 5:44:20 PM UTC, Patrick Whitney <pwhitney at luminoso.com> wrote:
>We tested with both, and experienced the same behavior using both
>strategies:  an abandoned DLM lockspace.   More than once, within this
>forum, I've heard that DLM only supports power fencing, but without
>explanation.  Can you explain why DLM requires power fencing?

The main part of dlm runs inside the kernel, and it is very hard to impossible to return it into a vanilla state programmatically. Espesially if filesystems like gfs2 run on top. iiuc Sistina originally developed dlm mainly for their gfs1, and only then for lvm. Things changed, but original design remains I believe.

>On Mon, Oct 1, 2018 at 1:38 PM Vladislav Bogdanov
><bubble at hoster-ok.com>
>> On October 1, 2018 4:55:07 PM UTC, Patrick Whitney
><pwhitney at luminoso.com>
>> wrote:
>> >>
>> >> Fencing in clustering is always required, but unlike pacemaker
>> >lets
>> >> you turn it off and take your chances, DLM doesn't.
>> >
>> >
>> >As a matter of fact, DLM has a setting "enable_fencing=0|1" for what
>> >that's
>> >worth.
>> >
>> >
>> >> You must have
>> >> working fencing for DLM (and anything using it) to function
>> >correctly.
>> >>
>> >
>> >We do have fencing enabled in the cluster; we've tested both node
>> >fencing and resource fencing; DLM behaved identically in both
>> >scenarios,
>> >until we set it to 'enable_fencing=0' in the dlm.conf file.
>> Do you have power or fabric fencing? Dlm requires former.
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