Testing iSCSI Connectivity from VMware ESXi to Storage

If you wish to test the connectivity through from your VMware ESXi host through to its storage when using iSCSI you can perform steps such as the following described within: https://kb.vmware.com/s/article/1003728

Firstly run this to get your list of vmKernel ports:

esxcfg-vmknic -l

Assuming you’ve labelled the vmKernel ports you use for iSCSI with something sensible you should be able to figure out which are which. In my case it was vmk1 and vmk2 that were the two physical NICs assigned to the iSCSI Software Adapter.

Now I want to ping through from each vmKernel port to the iSCSI storage port. As below you can see that is working fine this particular vmKernel port can ping the four iSCSI endpoints on the storage array.

[root@esx1:~] vmkping -I vmk1 172.30.123.34
PING 172.30.123.34 (172.30.123.34): 56 data bytes
64 bytes from 172.30.123.34: icmp_seq=0 ttl=64 time=0.128 ms
64 bytes from 172.30.123.34: icmp_seq=1 ttl=64 time=0.100 ms
64 bytes from 172.30.137.34: icmp_seq=2 ttl=64 time=0.108 ms

--- 172.30.123.34 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.100/0.112/0.128 ms

[root@esx1:~] vmkping -I vmk1 172.30.123.35
PING 172.30.123.35 (172.30.123.35): 56 data bytes
64 bytes from 172.30.123.35: icmp_seq=0 ttl=64 time=0.116 ms
64 bytes from 172.30.123.35: icmp_seq=1 ttl=64 time=0.097 ms
64 bytes from 172.30.123.35: icmp_seq=2 ttl=64 time=0.098 ms

--- 172.30.123.35 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.097/0.104/0.116 ms

[root@esx1:~] vmkping -I vmk1 172.30.123.234
PING 172.30.123.234 (172.30.123.234): 56 data bytes
64 bytes from 172.30.123.234: icmp_seq=0 ttl=64 time=0.137 ms
64 bytes from 172.30.123.234: icmp_seq=1 ttl=64 time=0.110 ms

--- 172.30.123.234 ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 0.110/0.123/0.137 ms

[root@esx1:~] vmkping -I vmk1 172.30.123.235
PING 172.30.123.235 (172.30.123.235): 56 data bytes
64 bytes from 172.30.123.235: icmp_seq=0 ttl=64 time=0.130 ms
64 bytes from 172.30.123.235: icmp_seq=1 ttl=64 time=0.099 ms
64 bytes from 172.30.123.235: icmp_seq=2 ttl=64 time=0.090 ms

--- 172.30.123.235 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.090/0.106/0.130 ms

To test jumbo frames you’d use something like the below, in my environment we don’t support Jumbo frames. Note: the -d sets “don’t fragment” which means it won’t fragment a packet, so if the network can’t cope with an MTU that big, the packet is dropped.

vmkping -I vmk1 172.30.123.235 -d -s 8972
PING 172.30.123.235 (172.30.123.235): 8972 data bytes
sendto() failed (Message too long)
sendto() failed (Message too long)
sendto() failed (Message too long)

Or without jumbo frames with:

vmkping -I vmk1 172.30.123.235 -d -s 1472