[Linux-cluster] virtualization on top of Red Hat cluster

Paolo Marini paolom at prisma-eng.it
Fri Jan 23 17:04:00 UTC 2009

We have a conceptually similar Cluster with cehaper HW working since one

1. 2 HP machines with RAID HW and multiple disks providing iscsi with
channel bonding, one for the working GFS fs and the other one for backup
GFS, SW is openfiler 2.2, ethernet channel bonding

2. 3 Dell machines, single Xeon quad core, running Centos 5.2 with
ethernet channel bonding and acting as xen servers in a single cluster

3. Services are implemented on a separated cluster, running on XEN virtual
machines on top of the real HW cluster. XEN virtual machines are loaded
from GFS (to be able to recover/relocate virtual machines)

4. XEN virutal machines mount a GFS filesystem (single filesystem ->
multiple access -> single backup -> better disk optimization !!!) and
provide their services: samba, dns, nfs, applications like wikis and SVN

5. Recovery is done via IPMI fencing, available on most pizza boxes, for
real HW cluster.

6. Recovery is done via XEN VM fencing on virtualized cluster

May be performance could be a bit better, but nothing more could be asked
with the cheap HW. The idea is that the whole cluster budget is less than
the price of a SAN box.

There is a nice tutorial on the RedHat magazine on the implementation of a
similar cluster, with lot of user comments.

Ciao, Paolo

> We would like to find out if there are other folks attempting to do what
> we are trying to do.  We are having all kinds of problems.
> We are trying to set up an 8 node cluster and run a number of virtual
> machines on top of this cluster.  The boxes are running Red Hat 5 and we
> are using Xen.
> Before going into the actual issues we are running into, I thought we
> should first find out if there are others who are doing this, or
> attempting to do this.
> This includes a separate virtual server for the following services:
> squid, ldap, mail server, dns, samba, email and a handful of
> Xservers/application servers.
> The specific hardware includes:
> 8 Dell 19150 nodes w/ rh5.2 xen
> Each node has 32GB of ram and 8 cores (xeon 2.66)
> EMC San CX-310
> 2 Brocade 5000 fibre switches
> Any feedback from anyone attempting or currently running a similar
> solution (virtualization on top of cluster) would be greatly appreciated.
> --
> Until later, Geoffrey
> Those who would give up essential Liberty, to purchase a little
> temporary Safety, deserve neither Liberty nor Safety.
>   - Benjamin Franklin
> --
> Linux-cluster mailing list
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