Topic
5 replies Latest Post - ‏2013-12-12T14:54:51Z by Novikov_Alexander
Diego Bell
Diego Bell
3 Posts
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Pinned topic DS3512 strange behaviour

‏2013-12-09T19:00:03Z |

Hi,

     I am experiencing a very strange problem with my DS3512 dual controller.  I have two hosts IBM x3550M4, with Windows 2012 and one LSI SAS HBA.  Because I have now only one HBA on each server, I have connected both mini-SAS cables to controller A.

I used the Mega-RAID LSI software to correctly identify the WWNs for creating the hosts.  I created a storage partition, created the two hosts, and a LUN.  I mapped the LUN to the hostgroup, in order to be shared by both hosts.  The LUN is using the A controller for ownership/preferred path.

Inside the Windows 2012 servers, the LUN is correctly identified an seen by both.

This is where the problem begins: the logical unit is acting as if it were two completely different disks.  If I create a file or folder in one server, the other server does not see any changes.  I went to the other server and made the same test, and files and folders are only seen by the server that was created.

I tried another LUN, this time with FAT file system in order to avoid things like ownership and permissions, but the result is exactly the same.  Files and folders created are only seen by the server that created the file or folder.  Very strange!

Any ideas?

Thanks in advance,

Diego

Updated on 2013-12-09T23:56:15Z at 2013-12-09T23:56:15Z by Diego Bell
  • Novikov_Alexander
    Novikov_Alexander
    1398 Posts
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    Re: DS3512 strange behaviour

    ‏2013-12-10T01:58:06Z  in response to Diego Bell

    Dear Diego,

    nothing strange, all worked as designed. Read the documentation and redbooks before configuring server.

    You must use cluster services on your Windows servers in case you want to use share LUNs for both servers.

    For example. read section "Microsoft Cluster configuration with DS3500":

    IBM System Storage DS3500 Introduction and Implementation Guide
    http://www.redbooks.ibm.com/abstracts/sg247914.html

    BTW, you must connect hosts to both controllers of your dual-controllers DS3512.

    Good luck,
    Alexander Novikov
    Russia, Moscow

    • Diego Bell
      Diego Bell
      3 Posts
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      Re: DS3512 strange behaviour

      ‏2013-12-11T09:40:23Z  in response to Novikov_Alexander

      Alexander,

                         Thanks for your advice.  As you said, everything is working fine, it was my mistake.  I am used to work with VMWARE and VMFS, it supports mapping the same LUN to more than one host.  I didn't know that Windows do not support this kind of sharing :)

      I have followed your advice, created a cluster and now everything is working as expected.

      Kind regards,

      Diego

      • Novikov_Alexander
        Novikov_Alexander
        1398 Posts
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        Re: DS3512 strange behaviour

        ‏2013-12-12T14:54:51Z  in response to Diego Bell

        Hi Diego,

        you are welcome.

        Regards,
        Alexander Novikov
        Russia, Moscow

         

  • sdenham
    sdenham
    53 Posts
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    Re: DS3512 strange behaviour

    ‏2013-12-10T23:17:41Z  in response to Diego Bell

    Diego -

    As Alexander has pointed out, you need a cluster-aware file system to make this work.  Otherwise the individual servers do not know that the data they have cached from the disk has been modified. Not only do you not see content from one server on the other, but at some point you will see the file system become corrupted when the two servers modify something independently.

    If you stop one server, create contents on the disk, and then reboot the second server, you will see identical content.. until one of the servers writes at which point the two will be out of sync again. 

    • Diego Bell
      Diego Bell
      3 Posts
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      Re: DS3512 strange behaviour

      ‏2013-12-11T09:42:48Z  in response to sdenham

      Sdenham,

                         Thanks for your help!  As Alexander and you pointed out, it was my mistake trying to make it work like a VMFS LUN.  I have followed Alexander's advice, created a Windows cluster and now everything is working fine.

      Kind regards,

       

      Diego