We followed this KB doc to disable delayed ack: https://kb.vmware.com/s/article/1002598. While this looks like it works, when you grep the iscsi initiator database it shows for one iscsi connection that it is still enabled. So I found this solution: https://www.virtual-allan.com/disable-delayed-ack-for-iscsi-on-esxi-not-always-working/ . This doesn't work either because when you go to remove all static targets it fails with the same connection that is still enabled saying that the path is busy. Well we are booting off our SAN so this is not a surprise. So what steps do I have to take to disable delayed ack for the iSCSI target pointing to our boot volume? Yes, I have an open ticket with VMware but they haven't found a solution yet either. Anyone else hit this? We are currently on ESXI 6 build 9313334. TIA!
After you have remove all static and dynamic targets you have to reboot ESXi and than configure SAN iSCSI connectifity again. You dont need to reboot your SAN because its ESXi which "remember"its connection details. We are a iSCSI shop since 2008.