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  • 1.  Unable to add RDM to the second host

    Posted Aug 26, 2014 02:37 PM

    Hi all,

    I have a problem - maybe quite basic, but I'm not VMware expert and after 3 hours of googling I decided to ask.

    My setup: two HP P2000 G3 iSCSI arrays, 3 DL380 Gen8 hosts. Running VMware 5.5, with vCenter, licensed Essentials version. HA is currently turned off. No production servers for now.

    What I'm trying to do: create Centos 6 cluster, with shared storage from P2000 array. Basic setup is done, now I need shared LUN from the array to be plugged in into 2 virtual machines. And here starts the problem, I figured out I need RDM, possibly with shared scsi bus adapters, but it will let me add RDM only to one machine.

    It goes fine on the first virtual machine, but when I try to add this to the second one - there is nothing on the list. I tried physical, virtual, etc but nothing seems to help.

    Any input appreciated - how can I add the same RDM (200GB LUN) to the second machine?

    Many thanks

    Chris



  • 2.  RE: Unable to add RDM to the second host

    Posted Aug 26, 2014 03:22 PM

    Chris,

      Vmware filters out used luns by default.  You will need to turn off the filter temporarily.  See the RDM filter item below

    VMware KB: LUN filtering mechanism during RDM creation



  • 3.  RE: Unable to add RDM to the second host

    Posted Aug 27, 2014 01:44 PM

    Andre is right, I forgot you just add the VMDK, but it is good to know about how the storage filters work anyway :smileyhappy:



  • 4.  RE: Unable to add RDM to the second host

    Posted Aug 26, 2014 05:18 PM

    Welcome to the Community,

    What you see is the correct (default) behavior. When you add a LUN as an RDM to a VM, an RDM mapping .vmdk file is created. To add the same RDM to another VM, you'll need to select "Add an existing virtual disk" and use this mapping .vmdk file.

    André



  • 5.  RE: Unable to add RDM to the second host

    Posted Aug 27, 2014 11:15 AM

    Many thanks guys. It could be more intuitive or at least better documented, the idea is quite awkward to me. But it worked and I can now start digging into clustering.