1. You are experiencing latency on your iSCSI storage array
2. You are seeing iSCSI aborts in the ESXi host
VMware vSphere ESXi
The physical switch ports in which the ESX and the array interfaces are connected must have flow control enabled. Failure to do so can cause TCP level packet retransmits or iSCSI-level abort tasks.
1. All vmnics used for iSCSI must have the same speed on the ESXi host
2. All hosts in the cluster must utilize physical NIC adapters from the same manufacturer
3. All vmnics for iSCSI must operate with the same driver and firmware version.
4. Flow control should be enabled on the vmnics
NOTE: Consult your storage vendor before enabling flow control to see if they recommend flow control to be enabled for when configuring iSCSI to their array.