Virtual Disk not on preferred path due to failover - MD3200

Hello danbrown1888,

In MDSM you can change the preferred path back to the correct controller or change the owner to the controller that the VD is on. Just right click the virtual disk and under change you change the current owner, which also changes the preferred owner. Only when a disk is on a non-preferred controller does it let you change controller without changing the preferred (you can then chose to just change the preference or change the disk to the other controller).

Also you state that when you do a scan on VMware that the storage isn’t getting seen & times out.  That sound like your data store is only getting seen by one controller and not both as if that happens when the data store move from primary controller to secondary. I would confirm that your data store has access to both controllers so that if you’re VD moves from one controller to the other it will not lose connection to the data store.

  Please let us know if you have any other questions.

Excellent, I came to the same conclusion about 5 minutes ago.  I see the exact option you are referencing.  Is this a safe operation to perform with live servers or would I need to shut everything down first and do it off hours?  Also, could you please elaborate on how to make sure that both controllers have access to the datastore?  Thank you for the help!

Hello danbrown1888,

Yes you can change the ownership while the servers are active it will not impact production as it will cache the changes and write them to the VD once changed which is quick.

For your data store you need to have a minimum of 2 cables from each controller on the MD to the server.  if you could take a screen shot of your Vswitch for your iSCSI as I would like to make sure that the connections are set correctly.

 Please let us know if you have any other questions.

Hi Sam

Here is the screenshot:

Does that look ok to you?

Perfect, thank you for all of your help!

Good morning, I hope its ok if I bug you with another question on this topic.  I reviewed the guide and I'm planning to head out to our datacenter to rewire the san in a couple of weeks.  For now I have to try and get it working as well as I can until I can get there.  I found that it failed over again to the second controller last night and I was wondering if you could help me track down the root cause of the failover.  While I understand it is not setup correctly it had been working reasonably well for more than 6 months in the current configuration.  I am unsure why it is failing over to the second controller and wanted to see if that could be addressed until I can travel there and redo the wiring.  Thank you in advance for any further help you could provide!

Hello danbrown1888,

I sure can.  I will send you an email.  I need you to pull a support bundle from your MD so that I can review it & let you know what I see.

Please let us know if you have any other questions.

Hello Sam,

I have problem "Virtual Disk Not On Preferred Path" the same with danbrown1888,

Here is my screenshot:

Does that look like setup is not correct ?

Hello suherman,

The alert on the system is due to a virtual disk not being on the preferred path. When virtual disks are created, they are assigned to one of the two controllers as a preferred communication path. If that path is not available – due to a network issue, controller reset, etc. – the array will communicate via the alternate controller. In some cases the communication does not shift back to the primary path when it becomes available again.  To correct this you just need to manually redistribute the virtual disks back to their preferred paths.

To redistribute virtual disks:

1.            Open Modular Disk Storage Manager (MDSM)

2.            Click on the Support tab

3.            Select Manage Raid Controller Modules

4.            Click on Redistribute Virtual Disks

•             You will get an alert telling you that this will disrupt communications if you do not have the multipath drivers installed. You can ignore this message and proceed. If you still have access to the virtual disk that is not on preferred path, you have multipath drivers installed

Please let us know if you have any other questions.