Multiple LUNS

[tjg091]

We are in the process of testing vmotion in our environment and I have 2 questions.

1. To vmotion between two hosts, do they have to both be the same version of Vmware? We have a 5.1 and a 4.1 host that we would like utilize vmotion with.

2. In our testing scenario, the 5.1 host is brand new with only a vcenter appliance guest installed on it. The 4.1 host has a few production guests running on it with an existing SAN LUN configured. Can an additional  LUN be presented to the 4.1 host to allow for testing with the 5.1 host?

Thanks

TJ

[eeg3]

You can vMotion between ESXi 5.x and 4.x, and mixed clusters are fully supported. Caveats being that virtual hardware 8 and VMFS-5 are not supported on ESXi 4.x. Source: Mixing ESX/ESXi Versions in an HA/DRS Cluster

I don't see why you wouldn't be able to add an additional LUN, as long as you use VMFS-3 if you want it to work across versions.

[tjg091]

If one of the VM hosts already has a working LUN and datastore assigned to it will adding another LUN (for shared storage with another VM host for vmotion) cause any problems? I need to know this for sure as I do not want to disrupt the existing datastore.

Thanks,

TJ

[JayhawkEric]

TJ,

You can add as many LUN's to each or both host as you want to, up to the maximum for each version.  The way to set this up will depend on the type of storage you're using (NFS, iSCSI, FC).

What you'll want to do is make sure they are both attached to the same vCenter and the LUN the VM is running on is available on both hosts.  If you want to create a new LUN and present it to both hosts you can but you'll need to SvMotion the VM on the 4.x host to the new LUN before you try to vMotion it to the 5.x host.

-Eric

[tjg091]

Eric,

Thanks for the reply. At our EMC SAN I receive the message when adding a new LUN to the storage group being used for vmotion.  "The following LUNS are already contained in a storage group: 54 

"Adding a LUN to multiple storage groups is not a recommended configuration because this will allow multiple hosts to have simultaneous access to the LUN". Is this a concern for vmotion or am I missing something?

Thanks,

TJ

[JayhawkEric · Accepted solution]

TJ,

vMotion requires both hosts to have access to the LUN at the same time.  ESXi handles who has a lock on the files.

EMC throws that error because a standard setup would be to have both ESXi hosts in the same storage group.  This is how I would set it up as well.  You don't have to though.

Regards,

Eric

[tjg091]

Eric,

So I can proceed at the informational message with no worries?

Thanks,

TJ

[JayhawkEric]

Yes.

[tjg091]

Thanks Eric!

[JayhawkEric]

Be sure to add the LUN on the 4.x host first (and then do a "rescan for datastores" on the5.x host).  If you add it on the 5.x host you must format it VMFS3 in order for the 4.x host to see the datastore.

Eric