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Quorum Disk uses entire disk.... RRS feed

  • Question

  • Hi
    I am using iSCSI shared storage and 2 clustered 2008R2 nodes.
    My iSCSI box (IBM DS3300) has 2 RAID 5's setup, one over the SATA disks and one over the SAS disks, each is approx 2TB.

    When I setup a Quorum disk in my cluster it uses an entire disk of 2TB, I have tried creating a volume on the disk of 1Gb but I cannot assign this as Quorum, it still takes the entire disk and makes it un-usable for datas storage.

    Is there a way of getting Quorum to use a volume rather than an entire disk?


    MCTS
    Monday, September 6, 2010 9:53 AM

Answers

All replies

  • A witness disk (quorum) must be independantly failing. That is, the entire disk must move from node to node. Essentially you should never attempt to present partitions to a failover cluster.

    On your iSCSI server create separate (smaller) LUNs or images on the underlying disks. You iSCSI software on the iSCSI server should be able to do this. The Windows Server cluster nodes then connect to the iSCSI server and "discover" the LUNs. Typically you'd make your Witness LUN 500MB-1GB.

    What storage software are you running on your iSCSI Server which has the physical disk array attached to it?

    Monday, September 6, 2010 11:28 AM
  • It's a IBM DS3300 disk array, it's not a server, just a bunch of disks in a box.

    http://www-03.ibm.com/systems/storage/disk/ds3000/ds3300/


    MCTS
    Monday, September 6, 2010 11:36 AM
  • Basically you want to create smaller Logical Disks within your array.

    Here is the basic steps from ibms site:

    http://www.redbooks.ibm.com/redbooks/SG247065/wwhelp/wwhimpl/java/html/wwhelp.htm

    Then map those logical disks (which could be say 1GB) to the hosts (your Window Server Failover Cluster nodes).

    It appears that there is an "automatic" feature which basically creates one big LUN. When in doubt never select any kind of "feature" which says it will do everything for you. :-)

    Monday, September 6, 2010 11:47 AM
  • Thanks, I had a hunch it was something along those lines but wanted to check before I started deleting logical drives.

    I have done what you suggested and all working now.


    MCTS
    Monday, September 6, 2010 12:25 PM
  • A witness disk (quorum) must be independantly failing. That is, the entire disk must move from node to node. Essentially you should never attempt to present partitions to a failover cluster.

    Stephen,

    Do you mean quorum disk doesn’t even need to be partitioned?

    According to http://technet.microsoft.com/en-us/library/cc770620%28WS.10%29.aspx

    Quorum disk should be (Windows Server 2008):

    - Use a small Logical Unit Number (LUN) that is at least 512 MB in size.

    - Choose a basic disk with a single volume.

    I.e. it clearly doesn’t even need to be formatted, but it has to be partitioned, right? ;-)

     

    From another hand (same article)

    If File Share Majority is used it needs only:

    - Make sure that the file share has a minimum of 5 MB of free space.

     

    How come quorum disk has to be half gigabyte at least, while file share needs only 5 MB of free space?

    Am I missing something big there?

    Friday, September 10, 2010 9:36 PM
  • Basically Rob had a external disk array which had been incorrectly configured. It wasn't really a quorum/witness disk problem.

    Witness disk should be formatted as NTFS with the default Windows block allocation size.

    Each Logical Unit (LUN) presented to a cluster needs to be accessable from all cluster nodes (unless it is a Geo-cluster but that's a different story). Each disk should be a "Basic" disk (not a Dynamic disk) and a single full sized volume configured on it. That volume then needs to be formatted with NTFS.

    A File Share witness doesn't store a full copy of the cluster database and log files.

    Saturday, September 11, 2010 3:08 AM