The situation is:
- I am running VMware ESX 3.5 (3 ESX Hosts w/ vCenter Server in a Cluster);
- I need five Virtual Machines to read from the same disk running a clustered file system;
- I cannot replicate data for each Virtual Machine due to capacity; and
- I need to avoid a single point of failure (sharing from a VM is not a viable option);
In a traditional system I would point two servers at the same LUN and used a clustered file-system and this is what I'm looking for an equivalent of inside of a virtualised environment.
I have a SAN and can use Raw Disk Mappings (RDM) from a VM to map to a LUN however there is LUN limit on the SAN and I am unable to establish a LUN for each Virtual Machine.
Is there a clever way around this or am I snookered?
More info:
I'm looking to run a clustered application and need to share file content and configuration between two Virtual Machines, about 50gb. This was previously done using a shared LUN on a SAN. I require both load balancing and HA of the machines. I do not have the capacity to replicate the data on each VM and the application cannot tolerate any sync-lag.
Essentially I "just" need a way to point each VM at a single LUN and allow the VM to then control that disk.
Licensed features include HA/DRS
Best Answer
Note: I've never done this before.
The shared storage RDM should be possible, although having five nodes accessing it could introduce hilarity.
The technique you want is similar to how two node Microsoft Clustering Services is implemented (with a shared quorum drive); VMware provide a documented method for how to achieve it.
The solution looks well documented, if a little hairy. I'd recommend building and testing it in a lab before considering letting it anywhere near your production cluster.
Good luck.