Hi folks, I’m tearing my hair out over this one and I don’t have much as it is, so I’m hoping you can help! Thus far, my googling has gotten me nowhere. (This involves Cisco UCSB-B200-M4 blades and a Nimble SAN, connecting via Fibre Channel.)
I’m in the process of moving six ESXi 5.5 hosts out of vCenter 5.5 and into vCenter 6.5, where I’m upgrading them to ESXi 6.5. No VM downtime is permitted. The problem is that when I try to add a host to VC 6.5, I get this error (for example):
Datastore ‘MyDatastore‘ conflicts with an existing datastore in the datacenter that has the same URL (ds:///vmfs/volumes/58e7c84b-122de5b1-44be-0025b511a08c/), but is backed by different physical storage.
The error is wrong: there is no different physical storage involved here. The hosts are all members of the same initiator group on the same SAN, pointing to the same LUNs. Also, weirdly, this error only shows up when adding some of the hosts. And when it does show up, it consistently refers to same three datastores; the other datastores are apparently not problematic, for some reason.
Since I have plenty of redundancy on this cluster, I evacuated three hosts of their VMs, unmounted/detached/unpresented all the datastores, moved the hosts into VC 6.5, did a clean install to ESXi 6.5, then added the datastores back again. However, when adding the other three hosts I continued to get the same error.
Next step: since this is a datacenter-level problem, I created a new datacenter and added the other three hosts to it. I then tried to do a cross-datacenter vMotion to the upgraded hosts (I’m licensed for that, so that’s not an issue). This produced a different (but probably related) error:
Unable to access the virtual machine configuration: Unable to access file [MyDatastore] MyVM/MyVM.vmx
So basically, vCenter still thinks the datastores on [host A] are different from the identical datastores on [host B]. So when it tries to vMotion and checks whether the destination host can see the VM’s storage, the check fails.
Now I’m thoroughly stumped! What can I do to resolve this?