On the Sun Fire 280R, if the RSC card is configured properly, the log history during a boot will show a disk as having failed and then reports it as ok:

NOV 26 14:36:29 e280r-hw: 00040002: "Host System has Reset"
NOV 26 14:36:30 e280r-hw: 0004000b: "Host System has read and cleared bootmode."
NOV 26 14:36:54 e280r-hw: 00010000: "Disk 0 Failure."
NOV 26 14:37:54 e280r-hw: 00010001: "Disk 0 OK."                        

This is a normal situation for this system.

What is happening is the disk is not ready to be probed but the system is looking for the disk.

The system finds the disk, but it has not fully spun up, therefore it reports the disk as having a failure.

NOV 26 14:36:54 e280r-hw: 00010000: "Disk 0 Failure."            

Once the disk has gotten to full speed the system sees the disk as ok and reports it as:

NOV 26 14:37:54 e280r-hw: 00010001: "Disk 0 OK."            

The disk has not failed,. no need to replace.