[Ocfs2-devel] [PATCH 3/4] re-enable "ocfs2: mount shared volume without ha stack"

[heming.zhao at suse.com]

Hello Mark,

On 8/1/22 01:42, Mark Fasheh wrote:
> Hi Heming,
> 
> On Fri, Jul 29, 2022 at 6:15 PM Heming Zhao via Ocfs2-devel
> <ocfs2-devel at oss.oracle.com> wrote:
>>
>> the key different between local mount and non-clustered mount:
>> local mount feature (tunefs.ocfs2 --fs-features=[no]local) can't do
>> convert job without ha stack. non-clustered mount feature can run
>> totally without ha stack.
> 
> Can you please elaborate on this? Local mounts can run without a
> cluster stack so I don't see the difference there. We have

I am using pacemaker cluster stack. In my env, the trouble of the converting between
local and clustered mounts are only happening on cluster stack.

the non-clustered mount feature (Gang He commit: 912f655d78c5) gave ocfs2 the ability
to mount volume at any env (with/without cluster stack).
The 912f655d78c5 derived from SUSE customer complain: User wanted to fsck the backup
ocfs2 volume in non-clustered env. They wanted to access the volume quickly and didn't
want to take time/resource to set up HA stack. (by the way, pcmk stack at least needs
two nodes to set up a cluster.)

> tunefs.ocfs2 look for and join the cluster so as to avoid corrupting
> users data - that's a feature, not a bug. So what I'm seeing here is
> just opening us to potential corruptions. Is there a specific use case
> here that you're trying to account for? Are you fixing a particular
> bug?
> 

Tunefs.ocfs2 still needs HA/dlm stack to protect joining action. commit 912f655d78c5
works on non-clustered env, which needs other tech (eg. MMP) to protect corrupting.

 From my viewpoint, the non-clustered mount code is based on local mount code,
which gives more flexible than local mount. non-clustered mount uses unify mount
style align with clustered mount. I think users will like more to use non-clustered
mount than using tunefs.ocfs2 to change mount type.

Thanks,
Heming