> I want to build on Open Source tools a high availabitiy server to store
> my images, someone with suggestions? experiences plz. really aprreciate.
>
> Started to try Gluster but yesterday discussion pointed me very
> important things.
For Image storage you don't need a Cluster Filesystem. It even maybe a
performance bottleneck, as any Clusterfilesystem will need write locking over
the net.
What you really need is some kind of shared storage. That could be
Fibrechannel, Iscsi or (today not any more common) SCSI.
The shared storage must have redundant paths to be really high availability.
So that means: Redundant paths to the storage as well as redundant raid
controllers. (For the FC example: Dual HBA's, Dual FC Switch, Storage with
Dual Controller). For the path discovery use dm-multipath.
What I'm doing in the front:
Three server (all with dual FC HBA) with Scientific Linux 5.1 (a RHEL clone
like CentOS). The servers are members of a cluster (of course you need
servers with a BMC and IPMI over Lan for the fencing). On the clusternodes I
run clvmd (Cluster Logical Volume Manager) and rgmanager (Resource Manager).
The images are just Logical Volumes, they will not be mounted on the hosts.
The cluster locking is only needed for the lvm commands, so its no
bottleneck. Any node sees the same images, so on failover another node could
immediately restart the failed domU.
rgmanager handles nicely the failover of domU's.
If it's enough availability when you're domU's are up again after a host
failure after a few 10's of seconds, then that's it.
If you need a little bit more high availability, you could think of clustering
also domU's and define failover services on that cluster. There are rgmanager
scripts already in the distribution for a bunch of common services like nfs,
samba, http and so on.
Any software used in that setup is opensource. You could of course use other
distributions which support Redhat Clustering, but easiest way is to use
CentOS or Scientific Linux. Both have long term support and are available
without license costs.
Sincerly,
Klaus
--
Klaus Steinberger Beschleunigerlaboratorium
Phone: (+49 89)289 14287 Am Coulombwall 6, D-85748 Garching, Germany
FAX: (+49 89)289 14280 EMail: Klaus.Steinberger@xxxxxxxxxxxxxxxxxxxxxx
URL: http://www.physik.uni-muenchen.de/~Klaus.Steinberger/
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