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How to umount lofs file system in Service Guard?

 
Steven_Chen
Occasional Advisor

How to umount lofs file system in Service Guard?

Hi experts,

 

my customer have cluster environment that mount several LVs in same VG.

Some of these LVs are been mounted back locally as another path for application access. the type of file system mount is lofs.

the problem is when I shutdown service with cmhaltpkg to stop serviceguard, these file system did not umount via service guard script but the original LVs will been umount via serviceguard script, so I always face same problem on these LVs been report::

 

umount: cannot unmount {some_path} : Device busy
umount: return error 1.
 WARNING:   Running fuser to remove anyone using the file system directly.

of cause the final status of service stop is failed. 

 

How can I avoid this situation occurred everytime when I needs to stop service?

 

looking forward to hearing from you experts,

Thanks

1 REPLY 1
Matti_Kurkela
Honored Contributor

Re: How to umount lofs file system in Service Guard?

Before the underlying VG is deactivated for package failover, the lofs mounts connected to that VG must be unmounted; this means any applications using the lofs mounts must stop using them or die.

 

For regular filesystems, Serviceguard already has an optional logic to run fuser -ck to kill any users of the package filesystem, and retry the unmount. But this only takes care of user-space processes: a lofs mount is not a mere userspace process, so it can keep the filesystem "busy" even when the fuser command no longer finds any processes to kill. (You cannot remove a filesystem mount by killing something: you must unmount what you have mounted.)

 

The same applies to NFS shares: they are not identifiable/killable by fuser since the NFS server is a kernel-level service. Yet they can keep a filesystem "busy" and prevent unmounting.

 

If your lofs mounts are implemented by custom scripting, you may have to write a similar "kill-and-unmount" logic for the lofs filesystems to your custom scripts.

MK