Xen at scale

[David Becker <becker@cs.duke.edu>]

I'm using Xen for our cluster management project.  At the moment 219
xen-1.2 nodes  are up (my interest in multicast is to udpcast virtual disk
images to all those hosts).  At this time I'm just running two domains on
each host but that will be going up soon (as well as the total number of hosts).

For the most part all is well.  Sometimes a domain will spontaneously stop and
I've yet to figure out why.  The leading suspect is memory pressure.

My wish list based on my experience so far:
       HIGHMEM4G - This is my top wish, and I will work on it myself
            when I get a chance, though I can't say when that will be.
       halt - Xen is unstoppable!!!!   :-)
             We had an A/C outage the other night, and while trying to
             remotely shutdown sections of the cluster I discovered that
             halting DOM0 just caused xen to reboot.
       system info/logging -
           It would be very handy to have total phys memory reported
           somehow.   The cluster is heterogenous, and memory upgrades
           happen, and the net result is I rely on /proc/meminfo to know
           what is in each host.  The xenolinux meminfo just says what
           that domain was allocated.   Is total RAM reported somewhere
           I don't know?

           Viewing the vfr rules without resorting to xen_read_console
           would be handy as well.

           Getting xen console output to a log file would be useful.  
	   Running hundreds of xen_read_console is not so practical.
	   This would help in identifying those mysterious reboots.
           Most hosts in this cluster do not have serial lines or heads
	   attached.  I think I saw console output was changing in 1.3
	   so maybe this has been worked on already.

       multicast - as mentioned

       FreeBSD - I'd love a freebsd domain.  I know y'all said this was
           in the works.  Is there any current status?


Perhaps some of this is already there, and I just don't know.  More docs
are always welcome.  My own documentation track record is not so great so I
can sympathize on this one.


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