Is more iSCSI targets a bad thing for overall performance?

[fourg]

We have a bunch of 3 to 6 node StoreVirtual P4000 clusters that serve up their LUN's via iSCSI to a number of hosts.  My question is, is it benefecial to limit a LUN to just the hosts using it versus offering all LUN's to all hosts?  From a flexbility standpoint of course the latter, but from a performance point?

[Robert_SF]

We have several clusters with as many as 8 nodes and 8 members of server clusters.  Also numerous volumes. 70+ volumes as well. i would be curious to hear an answer to this.

[oikjn]

Are you talking about connecting them or just assigning them R/W access and not connecting them.  If you are talking about connecting them, I think that sounds like a bad idea as unless the servers are using a filesystem that supports shared storage then you are going to run into corrution problems.

As for limiting who is assigned to the LUNs, I would limit it simply for ease of administration and to prevent a server from potentially connecting to the wong LUN through a fat-fingered admin.

[fourg]

I'm asking about assigning them R/W and connecting them.  All of the hosts support the shared storage.

[oikjn]

what do you mean by support shared storage?  

I would not assign and would not connect hosts that are not supposed to be using a LUN to that LUN just because it seemed simpler.

For example, if you have a hyper-v cluster w/ CSV LUNs, I would connect all hosts to those LUNs, but I would not connect hyper-v hosts from another cluster to those LUNs as there is no benefit to this and only trouble could happen.

Can you detail what you are thinking of doing w/ the exactly what kind of hosts and LUNs?