Just a quick post showing a few commands that are great for troubleshooting issues with ISCSI on ESXI host:
the following cmd verifies that you can reach the TCP ISCSI port (2360) on the storage array from the host.
nc -z target_ip 3260
To test the san and switch configuration you can use the following cmd to ping a storage array with jumbo frames from a ESXI host:
vmkping -s MTUSIZE IPADDRESS_OF_SAN -d
the -d indicates “do not fragment”
vmkping: uses VMkernel to ping a device.
list LUN multipathing information:
esxcli storage core path list
List NMP Devices:
esxcli storage nmp device list