vSphere Storage Appliance

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  • 1.  Can you share a datastore across multiple Clusters?

    Posted Oct 23, 2012 07:13 PM

    I was wondering if you can share a datastore across multiple clusters without any locking issues. Single Datacenter, but multiple Clusters(Esxi 4 and 5). Luns to be shared across Clusters are VMFS3.



  • 2.  RE: Can you share a datastore across multiple Clusters?

    Posted Oct 23, 2012 07:19 PM

    Yes this is possible. You can even vMotion VMs between clusters, provided the hosts are compatible.

    André



  • 3.  RE: Can you share a datastore across multiple Clusters?

    Posted Oct 23, 2012 07:27 PM

    I thought so. I had our SAN vendor say they would be corruption---basically had the mirror the cluster format on our SANs and when mapping luns between them it errored. I explained that esx would take care of the locking issues. Just thought I would check. Thanks,,,



  • 4.  RE: Can you share a datastore across multiple Clusters?

    Posted Oct 24, 2012 05:33 AM

    Locking concerns are usually more around the quantity of VMs running on a datastore and if VAAI is supported, not how many clusters / hosts are presented. Your vendor may be thinking more around something like Windows failover clustering, which only allows one node to actively use the disk at once.

    Note: Without VAAI, the entire LUN is locked when a write needs to occur. With VAAI, the ATS primitive allows you to do sub-LUN locks for just that VM.



  • 5.  RE: Can you share a datastore across multiple Clusters?

    Posted Oct 24, 2012 02:12 PM

    Yes we have 1 SAN that suppors ATS,,the other will after a firmware upgrade. Excited to start using it. Will make a big difference, though we dont see a lot of reservation problems. thanks!



  • 6.  RE: Can you share a datastore across multiple Clusters?
    Best Answer

    Broadcom Employee
    Posted Oct 24, 2012 02:15 PM

    Some pros and cons can be found in these articles...

    http://www.yellow-bricks.com/2010/02/05/storage-masking/

    http://www.yellow-bricks.com/2012/09/21/say-goodbye-to-the-transfer-lun-aka-swing-lun-aka-stepping-stone/

    Concerns would be an APD condition impacting more than 1 cluster, as well the ability for said LUN to perform when accessed from multiple hosts from multiple clusters.

    The original use case as a swing-LUN for migrating VMs between clusters but which is no longer necessary in vSphere 5.1 with enhanced vMotion functionality.

    HTH

    Cormac



  • 7.  RE: Can you share a datastore across multiple Clusters?

    Posted Oct 24, 2012 02:33 PM

    Thanks, I forgot about that. I assume on non-shared storage the data is simply moved through the vmotion network?

    Also these clusters are 4.1 and 5.1,,,so i dont think this will work entirely for me. therefore i may have to use a swing lun.

    A



  • 8.  RE: Can you share a datastore across multiple Clusters?

    Broadcom Employee
    Posted Oct 24, 2012 04:54 PM

    Yes - its only available in 5.1.

    There is a great deep-dive on it here - http://frankdenneman.nl/vmotion/vsphere-5-1-vmotion-deepdive/



  • 9.  RE: Can you share a datastore across multiple Clusters?

    Posted Oct 24, 2012 05:54 PM

    Yes - a datastore can be shared at the storage level across multiple clusters - this is not dependant on 5.1, we have been able to do this forever.



  • 10.  RE: Can you share a datastore across multiple Clusters?

    Posted Oct 25, 2012 02:54 PM

    Thanks everyone!