[CentOS] does anyone have experience with clusters?

[Fabian Arrotin]

Rudi Ahlers wrote:
> Hi all,
> 
> I want to start experimenting with clusters, and I would like to use
> normal desktop grade hardware for this. I have some extra PC
> components lying around, enough to build 3 - 4 moderate desktops with
> a PIV / C2D CPU & 512MB - 1GB RAM each. All the machines should have
> at least a 100MB NIC, but I can add a gigabit NIC to the machines that
> doesn't have it if need be.
> 
> I have used Linux Heartbeat to failover a MySQL cluster before, and
> it's actually been running very well for about 3 years now. But, I
> want to start looking @ total clustering, with DRBD - where everything
> (not just MySQL) is being replicated across the 4 machines. I'm also
> intereated in load balancing.
> 
> Has anyone done anything like this?
> 
> The cluster will be running / hosting a few XEN Virtual Machines, and
> idealy if one PC / server dies (hardware failure / power failure /
> etc), then on of the other machines should still be running the
> virtual machines, i.e. no downtime. Is this possible? Can somone steer
> me into a direction where I can get more info on this?
> 
> My aim: to use common, cheap PC equipment & CentOS for the project, I
> don't want to spend any more money, and want to use what I have.
> 

So if i understand you correctly, the goal is to have a Xen farm running 
on multiple hosts ?
You can use the included clustering solution (conga) to do that but 
normally it needs a shared storage to store the domU's ..
What i've already tested is to use drbd with GFS2 so that all the local 
storage act like only one for all the nodes but that specific drbd part 
is not covered by conga. But i don't get the point about load-balancing 
? you were talking about xen domU's and previously about mysql ... i 
suppose mysql will be running inside of a domU ?
BTW the RHCS (conga) doesn't provide by itself a load-balancing solution
You can read the following article that was really interesting when i 
wanted to test that (except that it doesn't deal with drbd, but you can 
find informations on the wiki for that) : 
http://www.redhatmagazine.com/2007/08/23/automated-failover-and-recovery-of-virtualized-guests-in-advanced-platform

-- 
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Fabian Arrotin <fabian.arrotin at arrfab.net>
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