Sun Sparc Ultra 4 won't boot - disk errors

Hi all.
I am seeing in one of our less-used servers that it crashed and now won't restart. I get the message 'continue with normal startup or boot into maintenance mode'.

I go into maintenance and run fsck on /usr0 (mentioned in error at restart) it then reboots but goes right back to 'continue with normal startup or boot into maintenance mode'.

metastat reports:

metastat d36
Concat/Stripe
Size 28672520 Blocks
Stripe: 0
Device Start Block Dbase State Hot Spare
WARNING: /PCI@6,4000/SCSI@4,1/sd@0,0 (sd45):
Error for Command: load/start/stop
Requested Block: 0
Sense Key: not ready
ASC: 0x4 (LUN not ready), ASCQ: 0x0 FRU: 0x0

df -k shows nothing so not sure where to go from here.
I am not much of a unix admin so just curious as to what I can look into or do about this?

Thanks for all replies.

Jamie

check the error messages in /var/adm/messages

boot from cdrom, do fsck on the raw devices fsck -y -F ufs /dev/md/rdsk/d0 etc for all slices untill there are no errors (hope you have a good backup).
then, init 0, followed by boot

I got it back.
The d36 is a submirror so I resynched and was able to get the server back up.

Now I have to swap the disk and all should be good.

Thanks for all your replies.