Q. What are some best practices for designing iSCSI redundancy for Hyper-V?

Traditional NIC teaming is not considered a best practice for storage connections.

Some storage devices don't support the use of multiple connections per session (MCS). In these cases, your only option is to use Multipath I/O (MPIO).

Use MPIO if you need to support different load balancing policies on a per-LUN basis. This is suggested because MCS can only define policies on a per-session basis, while MPIO can define policies on a per-LUN basis.

Hardware iSCSI HBAs tend to support MPIO over MCS, as well as including other features such as Boot-from-iSCSI. When using hardware host bus adapters (HBAs), consider using MPIO.

MPIO isn't available on Windows XP, Windows Vista, or Windows 7. If you need to create iSCSI direct connections to VMs, you must use MCS.

While MCS does provide a marginally better performance than MPIO, its added processor utilization can have a negative impact in high-utilization Hyper-V environments. For this reason, MPIO may be a better selection for these types of environments.