iSCSI Host Limitations

[sduplooy]

Hi all,

We are in the process of researching iSCSI SAN's for our first ESXi environment. A lot of the SAN's we have looked at mention that they have a host limitation on the number of hosts you can connect to. Take for instance the HP MSA2012i. According to them it has a 16 host limitation. I spoke to our supplier and they say this is 16 physical OR virtual hosts.

I don't see how it can be virtual hosts? Surely if you we have a ESX server hooked up we can create as many virtual servers on there as we want because its still only one physical connection to the SAN? Can somebody clarify what these host limitations on the SAN's are as the suppliers don't seem to know.

Thanks!

[christianZ]

Host numbers limitation - as you guess this is the case (by many vendors) -

VM limitations - never heard

[christianZ]

...but if you use iscsi initiator inside a vm and connect to storage then that is a "host connection"!!

[Lightbulb]

Yeah that is true. I guess this get into that foggy area of when a VM is a VM and when it is a physical system (As it can be perceived by a third party asset).

Though if not using software iscsi in the VM, the limit is 16 hosts and then you can have as may VMs on those LUNS as good sense will allow.

[Ken_Cline]

...but if you use iscsi initiator inside a vm and connect to storage then that is a "host connection"!!

Yes. Basically, an instance of an initiator is a "host". Remember that, from the network, you can't tell the difference between a VM and a physical server - it's just an IP address.

If you need to provision more VMs, configure the iSCSI initiator within the ESX host and create VMFS volumes for the storage of your VMs.

Ken Cline

Technical Director, Virtualization

Wells Landers

TVAR Solutions, A Wells Landers Group Company

VMware Communities User Moderator

[sduplooy]

Thanks all, pretty much what I thought.

[Erik_Zandboer]

Hi,

Limitations like this are often from a performance perspective: lower-end iSCSI SANs simply cannot handle too many systems sucking data out of the SAN. For that to perform you need more spindles, more cache, more CPU power inside the SAN etc.

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