I am unable to mount the SYS volume. Get the following error message:

Pool SYS: System data I/O error 20203 (zio.c[431]).
Block 98784 (file block-98784)(ZID 2176)

I've tried rebuilding the SYS pool, but get an error referring to bad
blocks. I had one drive in a 4 disk RAID 5 array go defunct before getting
this error. This is a NetWare 6 SP5 server.

Any suggestions?