EMC SAN LUN extended but the server can’t see the expanded LUN space

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This topic contains 4 replies, has 2 voices, and was last updated by  JDMils 1 year, 2 months ago.

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  • JDMils
    Member
    #167217

    I have a Windows 2008 R2 Ent server which has an NTFS D-drive which was a 1200GB LUN on our EMC VNX5300 SAN. The DBAs asked one of the Systems team members to increase the LUN so that the WIndows partition could be increased to accomodate the growing database. The D-Drive is an MBR style partition.

    The Systems guy increased the LUN on the SAN to 2050GB but when he looked on the server, the available disk space in Disk Manager has not changed- there is no extra disk space to increase the partition on?

    I’m not sure what is going on. Normally when you expand a LUN the extra space is visible in Windows Disk Manager.


    wullieb1
    Moderator
    #245668

    Have you rescanned the disks??


    JDMils
    Member
    #251031

    Done that, rebooted the server a few times. Oh, it’s a Windows Failover cluster disk in case that makes a difference?


    wullieb1
    Moderator
    #245669

    Just noticed you extended the partition to 2050GB which is above the 2TB (2048GB) https://blogs.technet.microsoft.com/askcore/2010/02/18/understanding-the-2-tb-limit-in-windows-storage/

    Drop it back to 2047GB and see if it works


    JDMils
    Member
    #251032

    Thanks Wullieb1, but unfortunately can’t reduce a LUN on an EMC SAN that easily.

    So I mirrored the drive on the same SAN and presented the mirror-copy to another server but as a 2500GB LUN and instantly I could see the disk, broken into the following:

    * Partition 1 : 1200GB (formatted and used)
    * Box 1: 848GB unused
    * Box 2: 452GB unused

    I was then able to extend partition 1 so now I have the following:

    * Partition 1 : 2048GB (formatted and used)
    * Box 2: 452GB unused

    Interestingly, note the maximum size of the partition? 2048 – which is 2 bytes less than the allocated space on the original LUN!! I cannot do anything with the 452GB space as the MBR disk does not support more than 2TB, or should I say 2048GB, partitions!

    So it looks like you are correct- if the overall LUN is more than 2048GB then it will not be seen by the host- but it works as expected on the second host?

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