Do all nodes in a vSphere cluster have to see all LUNs?

[bewail]

I'm having intermittent problems with a 9-node vSphere cluster that is attached to both an HP EVA and HP MSA SAN.

EVA works fine, but with MSA we have intermittent problems with SCSI reservation errors. If left, one MSA controller typically ends up crashing.

I suspect that if fewer nodes were connecting to the MSA LUNs then the SCSI reservation problems might disappear or reduce. The MSA problems only occurred after load and the number of cluster nodes increased.

So is it okay to present the MSA LUNs to, say, just 4 or 5 of the cluster nodes?

I'm pretty sure that this would work in the sense that vSphere would be smart enough not to attempt to migrate VMs to nodes that have no access to that VM's files, but perhaps the cluster's DRS and HA logic assume that all LUNs on shared storage are visible to all nodes?

Obviously I could split the cluster into two halves and present the MSA LUNs to only one, but that seems less flexible.

The MSA SAN is second-line storage, so I could live with a reduced number of hosts being able to access it.

Thanks.

[mcowger]

DRS would do the right thing - this is a doable config.

That being said, # hosts isn't whats driving your reservations, its number of VMFS meta data operations....redeuce the # VMs / LUN on that MSA (better yet get rid of it) and you should be fine.

--Matt

VCP, vExpert, Unix Geek

[marcelo_soares]

The reservations you are seen also may exist because you have VMs residing on the MSA luns spreaded to all (or almost all) ESX's. You can try creating 2 clusters, one connected to each SAN (fewer to the MSA, more to EVA, or wathever, depending the number of vms residing on each SAN), and I think you will be resolving your problem in a better way.

Marcelo Soares

VMWare Certified Professional 310/410

Technical Support Engineer

Globant Argentina

Consider awarding points for "helpful" and/or "correct" answers.