Mike Branda wrote:
>> - Build a Xen hosting cluster (with RedHat clustering: cman/dlm or gulm
>> for locking), and write a script that sparks off Xen domains in a
>> particular order across the cluster. This is something I'm playing with
>> in my spare time here.
>>
> Are you talking about multiple box Xens or a single with virtual Xens?
>
Multiple Xen hosts, each running multiple Xen images.
> Right now there are at least 2 separate hardware hosts (masters and
> slaves) running each service like ntp, dns, nis so the hardware failure
> variable is reduced.
>
That's what I'm trying for here. With Redhat's clustering
(http://sources.redhat.com/cluster/), Xen
(http://www.cl.cam.ac.uk/Research/SRG/netos/xen/), OpenSSI
(http://www.openssi.org), and ATA over Ethernet
(http://www.coraid.com/support/linux/).
Add clustered lvm2 (CLVM) on top of network shared storage (either GNBD
or ATA-over-Ethernet), and lvm2 volume mirroring (with "lvmcreate -m")
or RAID1 mirroring within the Xen images, and you have a shared storage
area network for every node in the cluster. The best part: no need for
special hardware, just cheap PCs with IDE drives and some ethernet.
The best part of this: you can run OpenSSI (http://openssi.org) in the
Xen images, which gives you one "big virtual machine" that spans the Xen
slices on each physical node in the cluster. This has been called "XXen":
http://openssi.org/cgi-bin/view?page=docs2/1.9/debian/xen-howto.txt
With this, you can add/remove OpenSSI slices, and migrate Xen slices
between physical Xen hosts, allowing you to take hardware out of
production - 100% uptime is my goal. Should a cluster node die for some
reason, a XXen virtual machine would recover.
I'll be blogging about how I've managed to get this to work soon enough.
The entire process is documented in a little article I've been writing
along the way.
> Thanks for the ideas!
>
>
Glad to help!
- Ian C. Blenke <ian@blenke.com> http://ian.blenke.com
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