[NAME]: I am not sure as to what were the changes that were done on the unisphere but it is not recommended to make any changes to the iSCSI server when a session is established between target and the initiator. We have to note that during upgrade(graceful process) each SP will reboot twice and uses cluster resources to failover and might take 30-120sec for the services to failover to the peer SP, However if you want to test the realtime failover you may try disconnecting the eth adaptor or remove the SP out where the iSCSI server is running and the failover will takeplace instantenously. In a vSphere environment please makesure that VMware tools are installed on all the virtual machines which by default increases the disktimeout value to 180 sec (ESX 4.0 and later).  [NAME]:For High demanding machines it is better to take a downtime as increasing the timeout value will increase the recovery time and this is best recommended for machines that run medium/low load.  Regards, Sri
We have recently implimented all of the suggestions in the available VNXe High Availability document.  I am getting ready to plan our upgrade to MR2 on our VNXe3100 and was currious on what we can actually expect for our iSCSI VMFS volumes.  I have seen some discusions that the actual failover isnt "instant" and can take perhaps 30sec-2minutes.    From a VirtualMachine standpoint, what should we expect when running Software Upgrades on VNXe?  Can I continue to have the virtual machines running and not expect any issues on our vSphere Cluster accessing the datastores while the storage processers are rebooted?  Or should I do as we previoulsy and power down all the VMs and then run the VNXe software upgrade, reboot the storage processors and then power up the VMs?  
Realworld HA Expectations (vmfs)