Hi Johny, you will not lose any I/O during a failover, Netapp has very clever HA logic. When both controllers are running it is essentially like having 2 systems, each with their own memory, drives, networking, etc. When an event that triggers a failover to occur, the remaining controller has the ability to takeover the drives and logical structures (aggregates, volumes, etc) and it will them mimic the failed controller. Normally this transfer happens with very few lost pings, and well within any I/O timeouts of a guest OS. When running in failover mode the failed controllers IP's, name, and data area all served through the single controller, so there is a possibility for degraded performance IF you happen to be really pushing the system, but hopefully your reseller has sized your unit properly and this is not an issue. Always test HA before putting the system into production, and have qualified engineer verify the shelves are cabled correctly for mulitpath HA.
