[Linux-cluster] RHEL/CentOS-6 HA NFS Configuration Question

[Colin Simpson]

Sadly that doesn't work (usually). With nfsd the filesystem will still
refuse to umount (despite the force) as it's locked in kernel space
(where nfsd lives). And the service will just go to failed.

The best you can so is the probably self_fence="1" which is pretty
brutal and halts the node with the stuck fs mount, I believe.

Colin

On Thu, 2012-05-17 at 00:45 +0200, emmanuel segura wrote:
> Colin
>
> Use force_unmount options
>
> 2012/5/16 Colin Simpson <Colin.Simpson at iongeo.com>
>         This is interesting.
>
>         We very often see the filesystems fail to umount on busy
>         clustered NFS
>         servers.
>
>         What is the nature of the "real fix"?
>
>         I like the idea of NFSD fully being in user space, so killing
>         it would
>         definitely free the fs.
>
>         Alan Brown (who's on this list) recently posted to a RH BZ
>         that he was
>         one of the people who moved it into kernel space for
>         performance reasons
>         in the past (that are no longer relevant):
>
>         https://bugzilla.redhat.com/show_bug.cgi?id=580863#c9
>
>         , but I doubt this is the fix you have in mind.
>
>         Colin
>
>         On Tue, 2012-05-15 at 20:21 +0200, Fabio M. Di Nitto wrote:
>         > This solves different issues at startup, relocation and
>         recovery
>         >
>         > Also note that there is known limitation in nfsd (both
>         rhel5/6) that
>         > could cause some problems in some conditions in your current
>         > configuration. A permanent fix is being worked on atm.
>         >
>         > Without extreme details, you might have 2 of those services
>         running on
>         > the same node and attempting to relocate one of them can
>         fail because
>         > the fs cannot be unmounted. This is due to nfsd holding a
>         lock (at
>         > kernel level) to the FS. Changing config to the suggested
>         one, mask the
>         > problem pretty well, but more testing for a real fix is in
>         progress.
>         >
>         > Fabio
>         >
>         > --
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>
>
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