Multipath for iSCSI storage using one or two vlans and switches
I'm setting up a HP MSA P2000 SAN that has two controllers in it. I understand why you'd want each controller to plug into a different physcial switch for redundancy, but do you really need to have two vlans/subnets, one for each controller to connect to? Or can you just have one and do it all through a single vlan/subnet?
Fizicist
As you wrote, the idea of two controllers is so you can connect each one to a different switch. I'm not sure exactly by what you mean by "Or can you just have one". Do you mean one vlan or one switch. If you only want to have a single switch, that's fine. If one controller fails, the other will continue. Each controller is usually in it's own broadcast domain, so yes I'd split the switch into two vlans, one for each controller. Just keep in mind that if the switch fails, everything will come to a crashing halt. You can start with this setup and in the future just add the 2nd switch with no need to bring the setup down. In the setups I manage, I have single SAN's to single switches and multiple SAN's to multiple switches.
ASKER
In my case, I have two physical switches, and each controller connects to a different one for redundancy. But we have one vlan for all storage traffic. My question is, is there really a need to have two vlans? Or is there a reason you wouldn't want both controllers and sans all working off a single vlan network?
In your case you don't need two vlans. Treat each controller as it's own network. On the ESX hosts, you should setup iSCSI for both controllers. Just put the controllers on separate subnets from each other. After your done, your iSCSI setup should have both targets.
Check out...
http://www.vmware.com/pdf/vsphere4/r40/vsp_40_iscsi_san_cfg.pdf
and see if it helps.
Check out...
http://www.vmware.com/pdf/vsphere4/r40/vsp_40_iscsi_san_cfg.pdf
and see if it helps.
-->In your case you don't need two vlans.
-->Just put the controllers on separate subnets from each other
From a networking standpoint typically each IP subnet is in its own VLAN.
-->Just put the controllers on separate subnets from each other
From a networking standpoint typically each IP subnet is in its own VLAN.
ASKER
Yes, I was just about to ask what giltjr mentioned. You say I can have one vlan, but then to put my controllers on different IP subnets. Typically a vlan is correlated to a subnet.
What is the issue with having both controllers on the same subnet and same vlan as long as they are plugged into different physical switches?
What is the issue with having both controllers on the same subnet and same vlan as long as they are plugged into different physical switches?
ASKER
I'm just going to assume there are no issues with having both controllers use the same vlan and same IP subnet. The info above is kind of contradicting in saying I don't need two vlans but I need to have separate subnets.
Can anyone clear that up before I close this?
Can anyone clear that up before I close this?
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ASKER
I guess in my mind it wouldn't matter which vendor you have or if it is active/active or active/passive would it? It seems like it would be a general principal applied to storage networking.
I guess having separate subnets might be good in the case of if you have two subnets that each run on completely different hardware.
In any event, thanks for the info. I'll go ahead and close this out.
I guess having separate subnets might be good in the case of if you have two subnets that each run on completely different hardware.
In any event, thanks for the info. I'll go ahead and close this out.