MD3000i and Multipathing in ESX 3.5

[Athletic]

Hello.

We're in trouble setting up multipathing with MD3000i.

We've a dual controller MD3000i, with one Virtual DIsc configured. MD3000i is connected to 2 ESX 3.5 Hosts.

We want to assign a different controller/path to a each ESX Host.

MD3000i is MRU (Most Recent Used) in Path Selection policy in ESX by default, so We're unable to specify the path for each ESX Host. If we change to Fixed (besides we can see error messages in MD3000i log: array not optimal, Volume not on preferred path due to AVT/RDAC failover), after rebooting the ESX Host the policy changes back to MRU again.

When it use MRU, sometimes, it can happen that each host uses a different path, but this is not controlable.

Is it possible to assign a different path to each ESX Host?

Thanks!

[williambishop]

As far as I remember, MRU ignores preferred path....You would have to set it at the san side, I don't know how that will work for you.

[jmacdaddy]

MD3000i is asymetric active/active. Each virtual disk is owned and accessed by only one controller at a time. If you hard code a fixed path to a NIC on the other controller, you will get the non-optimal message in the array management software. I have mine setup with 4 virtual disks, two disks owned by controller 0 and two owned by controller 1. I then manually balance fixed paths to my virtual disks across all 4 NICs. I have to make sure though that each path is hitting a NIC on the active controller for that virtual disk.

[roundorange]

Hi jmacdaddy,

For your setup, are you able to share whether the 4 ports (2 per controller) are on the same IP subnet or they are in different IP subnets. If so, how are the 4 ports subnetted (i.e. each controller has it's own subnet or the 1st port on each controller on one subnet and vice versa)? Is there a best practise or good reading material regarding this?

Many thanks in advance,

[Razorhog]

Can anyone shed some light on this? I'm getting the "virtual disk not on the preferred path" message in the Dell Modular Disk Storage Manager. Here is my current set up:

I've also tried adding an additional vSwitch to each host with an iSCSI vmKernel on the other subnet, but it did not help.

Edit: just realized I was in the ESX 3 forum, this should go in the vSphere section

[AndreTheGiant]

You configuration is fine.

I suppose that you also have 2 different vSwitches for iSCSI, one for each iSCSI network.

On each datastore properties (under multipath) you must see 4 path (only one active for each datastore).

"virtual disk not on the preferred path"

This warning is caused by some path reconfiguration that can appear or when you try path failover, or when you change default policy.

Andre

[Razorhog]

It is working. Here is final configuration.

http://farm3.static.flickr.com/2451/3749803521_f351155730_o.jpg

[AndreTheGiant]

It is working.

Good for you

Andre