First let me say that I recommend reaching out to Nimble Storage Support -- I have always received unprecedentedly fantastic assistance.
What version of VMware ESXi and vCenter Server?
What version of NimbleOS?
Does the creation of the datastore fail even on newly created volumes?
Have you tried using the vCenter plug-in to automate creation of the volume and datastore? Same result?
What does the VMkernel and iSCSI Initiator configuration look like?
I'm getting an error attaching a new Nimble CS300 (iSCSI) to a new UCS B200 M3 blade. The blade can see the nimble and created volumes, but when I try to add volume as a Datastore I get an error.
"Cannot Change the host configuration: Call "HostDatastoreSystem.CreateVmfsDatastore" for object "datastoreSystem-86753" on vCenter Server "VCENTERSERVER" failed."
Anyone have a suggestion?