Re: [Xen-devel] [RFC] Making Xen cluster aware - locking domains on shared storage

[Maximilian Wilhelm <max@xxxxxxxxxxx>]

Nobody interested in this?

> These days I had the idea, that it should not be that hard to pimp
> 'xm' to check if a domain already is running somewhere in the cluster
> if there is a shared storage available.
> 
> The basic idea is the following:
> 
>   Consider a cluster of n (>= 2) Xen nodes which share some storage
>   (e.g. a SAN or NAS or whatever) where the storage for the DomUs is
>   located and where some piece of shared (cluster) filesystem is located, too.
> 
>   Let's asume further the shared file system is mountet to /xen_cluster
>   on all nodes.
> 
>   Now it would come in handy if xm (or maybe some other part of the
>   Xen univserse) could create some kind of lockfile on this FS to indicate
>   that a given domain is already running somewhere in this cluster
>   (maybe the Dom0 could be written into this file).
> 
>   This way it would be quite easy to prevent trouble from people
>   running Xen in this kind of environment, as on domain could only be
>   started once on the cluster.
> 
> 
> So I've made up there patches
>  * [0] Example options for /etc/xen/xend-config.sxp
>  * [1] for options parsing for /etc/xen/xend-config.sxp
>  * [2] Basic implementation of lockfile checking/creation during 'xm create'
>        phase. The interesting part (shutdown, destroy, reboot(?),
>        migrate, ...) is missig.
> 
> So what do you think about all this?
> 
> I guess there is no big resistance against the idea as such.
> What about the implementation approach?
> Is this somethings you could imagine as a direction to go to?
> Or maybe handle all of this internally to drop the dependancy of the
> shared file system?
> 
> [0] http://files.rfc2324.org/patches/xen/xend-config.sxp.diff
> [1] http://files.rfc2324.org/patches/xen/XendOptions.py.diff
> [2] http://files.rfc2324.org/patches/xen/create.py.diff

Ciao
Max
-- 
        Follow the white penguin.

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