There are two updates for Xsan 1.4.2: "Xsan 1.4.2 Update" and "Xsan Admin 1.4.2 Update". These are available from both Apple Support Downloads and Software Update.
Before installation
After Installation
To prevent an inconsistent volume state, you should unmount, stop, and run the cvfsck command on each Xsan volume after the MDCs have been updated with Xsan 1.4.2 Update.
Metadata Controller (MDC) software version
Your MDCs must always have software versions (both Xsan and Mac OS) that are the same or more recent than the most recent client versions. Specifically, if any client in your Xsan network is using Xsan 1.4.2 with Mac OS X 10.4.10 or later, then your metadata controllers (MDCs) must also be updated to Xsan 1.4.2 on the same version of Mac OS X.
Software Update may have referred you to this document. Because some updates are prerequisites for others, you may need to use Software Update more than once to get all available updates.
A standalone installer is available from Apple Support Downloads.
If you need to install the update on a remote computer, use the softwareupdate command-line tool.
See Xsan: Compatibility of SAN clients with Xsan and StorNext controllers.
The Xsan 1.4.2 update addresses numerous issues related to overall reliability, usability and compatibility. It includes specific fixes for:
The Xsan 1.4.2 Uninstaller removes Xsan, the Xsan Admin application, and Xsan documentation files. The Xsan 1.4.2 Uninstaller is appropriate version to use when uninstalling Xsan 1.4.x installations and can be obtained from Apple Support Downloads.
Note: Before removing Xsan, you should back up all of your data and volumes.
Xsan 1.4.x administrators can find Xsan 1.4 documentation here.