[linux-lvm] Distributed Locking of LVM

Digimer lists at alteeve.ca
Tue Aug 29 07:05:17 UTC 2017

On 2017-08-28 08:41 AM, Kalyana sundaram wrote:
> We have a shared iscsi disk at all our boxes, with one vg. We are using
> clvm to manage locks to create extend activate delete list.
> CLVM is tedious to manage especially especially due to reboot if locking
> is struck somewhere. Instead we are thinking of modifying file_locking.c
> to get lock with distributed store like zookeeper or redis and on
> success run the above command, on failure backoff and try again
> The external ocking code will sit at _file_lock_resource, case LCK_VG. 
> Do you think its risky. Is there some other way people handle it?

I think you're trying to work around a problem, instead of solving it.
The only time locking blocks with DLM is if a node entered an unknown
state and fencing wasn't setup or failed (in which case hanging is the
least bad option available).

A lot of thought and design went into DLM / clvmd. I would be cautious
trying to reinvent a wheel this complex. Instead, do you have any
indication why blocking occurs? Do you have fencing setup and working?
What cluster stack/version/OS are you using?

You might want to post on the clusterlabs list, too.

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