ohh i remember those days. Was using Xsan with 2 xserves attached to infortrend eonstors. I spent so long trying to get it stabilized and reformatted the entire FS so many times. Eventually got rid of osxserver and learned how to install gentoo linux on the xservers. Tracked all the issues to a faulty riser card in one of the boxes (but had to use linux to get the low level details)! Eventually went GPFS and trashed the xserve hardware as well.
Shared local storage, like for video production houses. At the time, it was ludicrously fast.
It also worked with Windows, Linux and Unix machines. Pretty much anything that supported Fibre Channel connections.