Re: [Xen-users] DomU Locking Mechanism?

[Thomas Halinka <lists@xxxxxxxxx>]

Hey,

you're searching for heartbeat2 with crm.

Thomas


Am Montag, den 09.03.2009, 23:53 -0700 schrieb Nathan Eisenberg:
> Hello,
> 
>  
> 
> I have a new 10 node XEN cluster I've built out using 3.3, and a
> dedicated iSCSI SAN.  The XEN configuration files are located on a
> volume on the SAN, which is exported to all Dom0s via NFS.  The system
> works great, but there is one major issue, and two minor issues which
> I have to deal with before I take this system into production.
> 
>  
> 
> The major issue:
> 
> I have not found a method that I like for preventing a DomU from being
> started on two nodes at the same time and clobbering the data.  I've
> been considering writing a script to manage lock files which are
> placed into the configuration store directory; these files could
> contain the hostname of the Dom0 where the DomU is running, which
> would solve my first minor issue.
> 
>  
> 
> First minor issue:
> 
> I haven't yet found a method for figuring out where DomU's are, short
> of running lots of xm lists or scripting something silly together.
> This hasn't been a problem in my 2-4 node clusters, but it won't work
> as this cluster scales out to its eventual size (20 nodes).  If I
> implement the lock file idea, this problem is solvable.
> 
>  
> 
> Second minor issue:
> 
> I recall that there was a way to change the behavior of the XEN daemon
> so that it would migrate DomUs on shutdown, rather than suspend them
> to disk.  However, I can't figure out what that was.
> 
>  
> 
> Third minor issue:
> 
> Has anyone developed a mechanism for ensuring that VMs are distributed
> evenly throughout the cluster?  IE, if I have 10 Dom0s, and 100 of the
> same DomUs with the same memory size and the same load, the mechanism
> should ensure that I have approximately 10 DomUs per Dom0.  If a host
> dies, it'd be nice to have something that figures out how to
> distribute the 10 DomUs throughout the cluster evenly, so that each
> Dom0 has 11-12 DomUs on it.
> 
>  
> 
> A lot of this is probably just scripting, but I suspect this is a road
> others have had to walk, and I'd just as soon not reinvent a wheel
> (especially knowing how bad my scripts usually are :-) )
> 
>  
> 
> I apologize for the length of this post!
> 
>  
> 
> Best Regards
> 
> Nathan Eisenberg
> 
> Sr. Systems Administrator
> 
> Atlas Networks, LLC
> 
> support@xxxxxxxxxxxxxxxx
> 
> http://support.atlasnetworks.us/portal
> 
>  
> 
> 
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