MSA 2012i dual controller failover behaviour

[CWeed]

We have a single controller MSA 2012i and are considering installing a second controller. I'm trying to clarify the behaviour of a 2 controller model.

Somewhere I read that a VDisk is "homed" to a specific controller. Our installation includes a single VDisk.

My query is: with 2 controllers, will the MSA failover to the second controller and maintain access to the single VDisk?

Thanks in advance for your help.

[fh-djb]

We had a 2012i in house for evaluation with 2 controllers. The way it handles failover is a little odd. What happens is that you can force failover through GUI, but you have to re-present the LUN's to the host once you've forced failover to the other controller.

Another test we did was yank a controller out of the chassis that had a vDisk presented to a host and was the owning controller for the vDisk. Oddly, the vDisk remained presented to the host, which leads me to believe that somehow the system "fools" the host into believing the controller is still available, but the 2nd controller actually takes over. Strange!

Keep in mind we were just playing around with one of these iSCSI SAN's and by no means am I an expert on how the thing works.

[Uwe Zessin]

> the system "fools" the host into believing
> the controller is still available

The other controller takes over the IP addresses of the failed controller.

[George Blessing]

>> "The other controller takes over the IP addresses of the failed controller."

Is this documented somewhere?

[Uwe Zessin]

Yes. See the "HP StorageWorks 2000 Family Modular Smart Array reference guide" (481599-003) starting on page 263.

[andy osborn_1]

Sorry to add on to this post but I have a question in the same line.

I assume the 2 switches and the interfaces they are connected to must be on different subnets, is that correct?

Also I see from page 264 of the document your refefence that if Controller B goes down Controller A will manage the vdisks (probably at a decreased performance). If the SAN switch goes down or if a network cable to Contorller B goes down, or even if a network cable plugged into the server gets unplugged will it also then switch over to the other controller?
If just a network cable from a server's SAN HBA gets unplugged the controller obviously wouldn't take over the IP of the other controller, since other servers are still using it normally.