Last week we released a new XenServer multipathing guide:
CTX136354–Configuring Multipathing for XenServer
This guide provides dramatically improved guidance about how to configure XenServer multipathing, including iSCSI, Fibre Channel, and ALUA. It also provides procedures to help you validate your configuration is correct. This guide significantly revises previous guidance, especially in relation to creating SRs for use with multipathing. Although, this guide applies to the XenServer 6.x family, it is probably helpful for all XenServer versions.
Here are a couple of highlights:
Testing Your Configuration (p. 55)
Procedures provided in this guide include ones to help customers validate their multipathing configuration has all of its paths active and also that the data on all paths is balanced. If multipathing is configured incorrectly, it is possible, in some cases, for both paths to be active but have less than optimal throughput or even have one path that barely works (but is still marked active). The procedures in this section help ensure this is not the case.
XenCenter’s Wildcard (*) Option (p.49)
(XenCenter SR wizard > Location Page > Target IQN box.) Do not select the wildcard option whenever it appears. Only select it based on the guidelines on pages 50-52. Using the wildcard option when it is not appropriate can actually slow down storage performance.
This guide also provides iSCSI HBA configuration, Fibre Channel zoning requirements, preliminary troubleshooting information, and list of additional references. As always, suggestions and feedback are welcome.