How to setup file recover from a SAN snapshot in cluster

Posted on 2011-05-09
Last Modified: 2012-05-11

I am trying to recover a file from a snapshot on my iSCSI SAN, Equallogic 4000. I have to Windows 2008R2 in a cluster connected to the SAN.

I am able to setup a fileserver on one HyperV node, and have the files on a LUN on the SAN. I can make a snapshot of the LUN and connect to the snapshot no problem. But when I try to set this up on the cluster, I can not connect to the drive from windows or the cluster manager.

The LUN is connected with iSCSI initiator on a windows 2008R2 server. In the server manager the disks are in reserved mode and I can not "Change drive letter and paths" on the drive. Am I doing something wrong, or is it not possible to connect to a snapshot while connected to the volume it is a snapshot of?

The snapshot is read/write and allows multiple connection.
Question by:edaj6
    LVL 41

    Expert Comment

    It might be possible to connect to the snapshot from a cluster node, but I would think that it would be a lot easier to do it from a different machine altogether. For example, add your PC to the ACL of the LUN for access to the snapshots only. You can them mount the snapshot to your PC.

    Author Comment

    The SAN and cluster nodes are on dedicated switches, no other servers/pc's/vm can connect to the LUN's. I can only connect to the web management from my pc. I thought it was better to keep it separated?

    Also, I may want to setup the same way to snapshot/recover for Exchange and SQL, then I would need for the cluster nodes or the vm to connect to the LUN. Would it be better to let the vm's access the SAN directly?
    LVL 41

    Accepted Solution

    I let me VMs access the SAN directly for file servers, SQL servers, and Exchange servers. Basically, anything where the ability to grow a volume on the fly or use any of the other SAN features with the server is a plus.

    I am confused as to where you have clustering and how your file server files are being stored. Are you clustering your Hyper-V hosts, do you have two VMs clustered together, or are you doing both?

    I am guessing by the question that at most you have clustering at the Hyper-V level, which means that you are probably storing your files on VHDs. Are you trying to get an earlier copy of the VHD, or an earlier copy of the files stored within the VHD?

    My SAN is on a pair of switches with VLANs that also have my VM and backup traffic. I do replication so the iSCSI traffic needs to go across the WAN. If I need to grab a snapshot I usually mount it using whatever non-clustered box I feel like using (usually physical, but can be virtual).

    Author Comment

    I have a cluster with to physical cluster nodes (hv1 + hv2). Hv1 + hv2 and the SAN are connected to switches. Other physical servers (DC) and Vm's are on another VLAN and cannot connect to the SAN.

    The file server is a VM on the cluster. The files are stored on VHD's on dedicated LUN's. The cluster node connect to the LUN using iSCSI initiator, and this drive is the mapped to the VM as a "Physical hard disk".
    I am trying to restore an earlier copy if a file.

    The cluster is not in production right now, I am still testing and open to other solutions. I like the idea of the files being directly on the LUN but I guess this is not supported with failover cluster.

    I don't understand how your Vm's connect to the SAN, do they have a virtual NIC for LAN and another for accessing the SAN using iSCSI initiator?

    My 2 cluster nodes have 6 NIC's.

    LiveMigration (crossed cable)
    Virtual1+Virtual2 teamed

     Switch1 setup
    LVL 41

    Assisted Solution

    My VM would have 3 NICs. One for the public network VLAN 1, and two for the iSCSI network VLAN 100. This allows the VM to use MPIO with the EqualLogic HIT Kit installed. It is completely supportable under Hyper-V Host clustering. I have been doing it since I went to Hyper-V clustering before R2 came out.

    In your situation as you have it, in order to recover a file you would need to mount the snapshot to a Hyper-V node, and then either mount the VHD to the Hyper-V node or dynamically attach the VHD to a SCSI interface of the VM. By my account it's a lot easier to skip the VHD file and save directly on the SAN and then any server that has access to the snapshot can mount it and grab the required files.

    For my file server, I have never gone to the SAN snapshot to do a recovery. Instead I use Windows 2003/2008/R2 shadow copies to store 64 shadow copies on another volume. It's much more space effecient than the EqualLogic. I use a dedicated volume for storing shadow copies because Windows may delete shadow copies stored on a volume experiencing high IO.

    Author Comment

    Excellent, thanks a lot, just what I needed.

    I added the two SAN NIC's to the Vm's and use the LUN directly from VM. Will consider shadow copies on fileserver.

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