Here's another gem of info... (OS 10.4.11 / XSAN 1.4.2)
A client recently changed all MDCs and clients' metadata connections from EN1 to EN0.
Afterwards, only the clients showed up in Xsan admin.
No MDCs ...?
The Fix:
On each MDC, the "/Library/Filesystems/Xsan/Config/role.plist" file must be edited to reflect the new ethernet port. This is not neccessary on the client side.
Also, until this is changed, you cannot add another mdc, or change the role of any client to an MDC.
FYI