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niriwoing
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vMotion RDM disk with IBM DS8000 in virtual mode

Hi,

I have 4 ESXi 4.1 U1 hosts connected to IBM DS8000 SAN. Each server has 2 FC ports for redundancy connected to an active/active array.

I had to P2V few servers with very large SAN LUN attached to it. So I P2Ved the local disks and then attached the SAN LUN as virtual RDM on VM. Everything is working fine except for vMotion. It gives an error "Virtual Disk 'hard disk 3' is a mapped direct access LUN and its not accessible". So, I referred to VMware KB article "http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=101621...". I checked the LUN numbers through vSphere client and found it is same on all servers.

But when I check my vml identifiers they appear to be different. Here is how the vml identifier looks like on all 4 servers for the LUN in question:

ESXHS01

naa.6005076305ffc7b1000000000000f146                          vml.0200000000600508e0000000005114cac05f7e790f4c6f67696361:6
naa.6005076305ffc7b1000000000000f146:1                        vml.0200000000600508e0000000005114cac05f7e790f4c6f67696361:7
ESXHS02
naa.6005076305ffc7b1000000000000f146                          vml.0200000000600508e0000000006175475a9d1df6044c6f67696361:4
naa.6005076305ffc7b1000000000000f146:1                        vml.0200000000600508e0000000006175475a9d1df6044c6f67696361:5
ESXHS03
naa.6005076305ffc7b1000000000000f146                          vml.0200000000600508e0000000006175475a9d1df6044c6f67696361:6
naa.6005076305ffc7b1000000000000f146:1                        vml.0200000000600508e0000000006175475a9d1df6044c6f67696361:7

Now, the problem is I cannot vMotion this VM to ESXHS02. I am assuming it is because of the difference in last digit. Can I somehow resolve this from host side? What configuration changes I have to do to get the vMotion working (if possible then without restart)? Also, each server has 2 vml identifiers for each LUN, is it because of the redundant FC adapters?

Thanks in Advance!!

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niriwoing
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Hi,

We found why we had this problem. When our storage admins assigned the LUN they assigned it to 3 ESXi hosts and then to the last host. Immediately they discovered that the LUN number for the same LUN is different on last host. So they unassigned the LUN from last host and assigned again with same LUN id. This is why the last host had different vml identifier for same LUN even after matching the LUN numbers on all hosts. After reboot the problem was solved.

We wanted to verify by recreating this problem in test environment. What we did was to create a LUN to be used as RDM and presented it to our 2 test ESXi hosts with different LUN id. As expected vmotion did not work. Then we changed the LUN id on one host to match it with other host. On 2 out of 3 occasions the host did not require reboot to resolve this issue. We had to reboot the server on one occasion to get it working again. Its bit strange. We are still trying to figure out why this happened. If anybody has any idea please let us know!

Thanks!

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