Troubleshooting when Formatting iSCSI VMFS Datastore Generates Error
Symptoms
vSphere reports the following error while attempting to format a VMFS datastore using a Pure Storage iSCSI LUN:
"HostDatastoreSystem.CreateVmfsDatastore" for object "<...>" on vCenter Server "<...>" failed
The LUN will report as online and available under the "Storage Adapters" section in the vSphere Client.
Diagnosis
This error can be due to improper configuration in the network path causing jumbo frames to be fragmented from the ESXi Host to the FlashArray.
How to confirm Jumbo Frames can pass through the network
Run the following command from the ESXi Host in question via SSH:
vmkping -d -s 8972 <target portal ipaddress>
If no response is received, or the following message is returned, then jumbo frames are not successfully traversing the network:
sendto() failed (Message too long)
sendto() failed (Message too long)
sendto() failed (Message too long)
There is an L2 device between the ESXi host and FlashArray that is not allowing jumbo frames to properly pass. Please have the customer check virtual and physical switches on the subnet to ensure jumbo frames are configured from end-to-end.
Solution
Make sure all network devices allow jumbo frames to pass from the ESXi host to the Pure Storage FlashArray.