Install Guide

10 Citrix XenServer with Dell SC Series Storage Configuration and Deployment | 3132-CD-V
Shared iSCSI storage using iSCSI HBAs
3.1.1 NIC bonding compared to iSCSI MPIO
NIC bonding improves XenServer host resiliency by using two physical NICs as if they were one. If one NIC
within the bond fails, the host network traffic will automatically be rerouted through the second NIC. NIC
bonding supports active/active mode, but only supports load balancing of VM traffic across the physical NICS.
Each virtual network interface will only use one of the links in the bond at a time. Load balancing for non-VM
traffic does not occur with NIC bonding.
Multi-Path Input/Output (MPIO) also provides host resiliency by using two physical NICs. MPIO uses round
robin to balance the storage traffic between all available storage targets on a Dell SC Series storage array. By
spreading the load between multiple SC Series storage targets, bottlenecks can be avoided while providing
NIC, subnet, and switch redundancy.
If all Front End iSCSI ports on the SC Series storage are on the same subnet, NIC bonding is the
recommended option because XenServer iSCSI MPIO requires at least two separate subnets. In this
configuration, all iSCSI connections will use the same physical NIC because bonding does not support
active/active connections for anything but VM traffic. For this reason, it is recommended that Front End iSCSI
ports be configured for two subnets. This allows load balancing across all NICs and failover with MPIO.