vSphere Storage Appliance

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  • 1.  Correcting LUN numbers for RDMs across hosts

    Posted Jun 11, 2012 03:46 PM

    I've discovered some inconsistencies in a vSphere environment (ESX 4.0 hosts) I'm looking to help migrate from.

    There are a number of RDMs configured where 3 out of 4 hosts have one LUN ID assigned, and the fourth has a different LUN ID.

    The result of this is an error when trying to vMotion an affected VM we get an error along the lines of "Virtual Disk 'Hard disk x' is a mapped direct-access LUN that is not accessible".

    I've seen a few articles (e.g. 1029786) that refer to removing disks etc. but that article is a little more confusing to me than I'd like it to be when potentially "destroying the mapping file" so I want to ensure I get things right!

    As per that article, I've verified that the 5th & 6th characters of the VML file aren't consistent but this is due to the storage having been originally provisioned with an incorrect LUN ID.

    (Storage is provided via iSCSI from physical FalconStor NSS appliance cluster.)

    I'm hoping the following should work to correct this issue for each affected VM:

    1. Shut-down the VM (can't vMotion it due to the issue)
    2. Cold-migrate it to a correctly configured host & power the VM back on
    3. Using the storage management console, change the LUN-mapping to the correct LUN ID for the RDM volume to the affected host (other hosts are correctly mapped)
    4. Rescan the HBA on the affected host
    5. Attempt a live vMotion back of the affected VM

    Should it be this simple or am I missing something critical?

    Regards,

    Paul



  • 2.  RE: Correcting LUN numbers for RDMs across hosts

    Posted Jun 11, 2012 04:44 PM

    Hello.

    Note: Discussion successfully moved from VMware ESX™ 4 to VMware vSphere™ Storage

    Good Luck!



  • 3.  RE: Correcting LUN numbers for RDMs across hosts

    Posted Jun 12, 2012 03:26 PM
    Actually, thinking laterally on this one, can I work-around the issue by simply changing the LUN ID on the host that isn't currently hosting the affected/running VM, THEN vmotion it over?
    Stupid idea or not?


  • 4.  RE: Correcting LUN numbers for RDMs across hosts

    Posted Jun 16, 2012 10:01 AM

    Hi pjapk

    >>There are a number of RDMs configured where 3 out of 4 hosts have one LUN ID assigned, and the fourth has a different LUN ID.

    Check with your storage guy or who allocated the disk from the array to make sure all the hosts groups are the same.

    Cheers

    David



  • 5.  RE: Correcting LUN numbers for RDMs across hosts

    Posted Jun 18, 2012 08:02 AM

    Guess who has become "the storage guy" ? :smileyhappy:

    I've already been all through them and  found a few inconsistencies which will need resolving but these two are the first ones on the list as I need to get at the host for maintenance (therefore need to get these VMs off it temporarily).