Re: [Xen-users] High availability and live migration with just LVMand hardware fencing

[Bart Coninckx <bart.coninckx@xxxxxxxxxx>]

On Thursday 20 May 2010 17:24:23 John Madden wrote:
> >> Note Jeff's note on SAN snapshots and gfs_tool.  His snapshots work
> >> because the OS is made aware of the need to flush caches and temporarily
> >> queue writes to the disk.
> >>
> >> John
> >
> > Would a "xm suspend" before the snapstho not accomplish this?
> 
> I think you mean "xm pause."  That pauses or freezes the domain, but
> does nothing more to it.  Anything in memory on the guest remains in
> memory, not flushed to disk.  You need something inside the guest that
> tells the kernel to flush everything, fsyncs, etc., then makes no
> further changes to the filesystem until un-frozen.
> 
> John
> 

In case of Windows HVM guests quite a challenge guess ... "suspend" in Vmware 
context I believe really tells the OS to suspend (I think because it relies on 
the installed Vmware Tools)

If GFS can bring something to the table for this, I'll check it out, but it's 
again one more layer of unsupported complexity to SLES. 

Thx John, quite insightful!

Rgds,

B.

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