Concurrent Access (ALUA?) to a datastore LUN with FC and iSCSI from ESX 4.1?

russ_witt · ‎2012-05-16

My customer has a single FC fabric for VM datastores because they have 20x0 class NetApps and use one FC interface for Host access and the second for disk. They need to add new servers on new FC ports but they have lost the password to the Brocade FC switch! In addittion we need to be able to maintain access to the storage from the ESX Farm while we recover the FC fabric. Therefore I need to mount the existing datastores via iSCSI or create new NFS datastores and vmotion the vms to them before I take down and recover the FC fabric.

Is it possible to get the ESX 4.1 server to see a NetApp datastore LUN via FC and iSCSI concurrently (ALUA?) or must I dismount the LUN from FC to mount it via iSCSI?

I could also create an NFS share and vmotion to it but they are not licensed for NFS. I could do a temp license but iSCSI is available already.

My thought was to disconnect the FC datastores restart all the vms on iSCSI accessed datastores then recover the FC fabric. Can ALUA help here?

sharmas · ‎2012-05-17

You can't access a LUN over both iSCSI and FC for the same host in case of vSphere. If I remember correctly that is only posible with Windows using the NetApp DSM software. I suggest you create a new LUN over iSCSI and vMotion the VMs. There are a couple of ways you can configure iSCSI. Follow the best practices from TR 3749 http://www.netapp.com/us/library/technical-reports/tr-3749.html

russ_witt · ‎2012-07-19

Sharmas,

Thanks! That answers it. I thought I remembered there being a use case that allowed concurrent access to a LUN via FC and iSCSI. Thanks for reminding me of the context.

When I think about the ESX implementation of MPIO I realize it is implemented within a single type of storage adapter and not across all storage adapters as in the Windows case you mention. Therefore ESX can multiplex paths within FC or iSCSI but not across both.

Thanks!