[Linux-cluster] Node fencing via 'ssh/shutdown -r now' possible

Lon Hohberger lhh at redhat.com
Wed Aug 22 16:28:36 UTC 2007

On Wed, Aug 22, 2007 at 05:00:19PM +0200, Brieseneck, Arne, VF-Group wrote:
> Hi all,
> Has anybody an idea if it would be possible to fence first via a
> controlled shutdown second fencing via fence_impi?

> The advantage would be, that the filesystem of the fenced node have a
> better chance to be intact after shutdown then power cut off.

The disadvantages are:

(a) it increases cluster recovery time by *minutes* at the very least
(how long do you wait before cutting the power?)

(b) it might hang during shutdown, seemingly responding to the shut-down
request but never actually reaching 'off' state...

(c) the node - if it's actually having a problem - could still write to
the disk while we're trying to fence it.  Some could argue that this
data might be bad (particularly if the node's problem is a bad memory
stick), and lessening the window for this is a good thing.

There are also some IPMI implementation-specific problems (bugs?)
preventing this from being possible.

-- Lon

Lon Hohberger - Software Engineer - Red Hat, Inc.

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