Virtual Machines have turned invalid

Products

• VMware vSphere ESXi

Issue/Introduction

Datastore is showing 0 MB in size

Environment

ESXi 8.0
ESXi 7.0

Cause

This is due to a MTU mismatch.

While we are able to ping the target with defragmented packet size of 1472 (1500 - 28 header), defragmented packet of 8972 (9000 - 28 header) fails.

[root@esxi##:~] vmkping -I vmk1 ##.##.##.## -d -s 8972
PING ##.##.##.## (##.##.##.##): 8972 data bytes
--- ##.##.##.## ping statistics ---
3 packets transmitted, 0 packets received, 100% packet loss

[root@esxi##:~] vmkping -I vmk1 ##.##.##.## -d -s 1472
PING ##.##.##.## (##.##.##.##): 1472 data bytes
1480 bytes from ##.##.##.##: icmp_seq=0 ttl=64 time=0.213 ms
1480 bytes from ##.##.##.##: icmp_seq=1 ttl=64 time=0.185 ms
1480 bytes from ##.##.##.##: icmp_seq=2 ttl=64 time=0.210 ms
--- ##.##.##.## ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.185/0.203/0.213 ms

Resolution

To resolve the issue, we have the following choices:

• Change the MTU size on the VMkernel NIC(s) and Virtual Switch configured for iSCSI traffic to 1500.
• Ensure MTU size of 9000 is at the following (if not, update it)
  a. ESXi side: VMkernel NIC(s) and Virtual Switch configured for iSCSI traffic
  b. Switch side: Relevant ports on the switch (Fabric Interconnects usually require MTU of 9216 as opposed to traditional Switches that will need MTU of 9000)
  c. Storage Side: Relevant storage array data ports

More information regarding iSCSI connectivity troubleshooting is available at Troubleshooting ESXi connectivity to iSCSI arrays using software initiators