Crash a system with a standby u nmounted disk and smartctl?

One of my systems has 5 disks (U320 scsi, not RAID) on of which is a hot 
spare, not mounted.  A while back one disk started to throw a lot of 
errors, so the hot one was mounted and restored from backup, and the 
failing one unmounted but left plugged in.

Later the bad disk was remounted briefly, to pull off a few files that 
were updated on that disk after the last full backup.  After that was 
done it was left hot but not (I believe) mounted.

There is a script on this system which periodically runs a long SMART 
test on all hot disks, mounted or not.  This weekend the system crashed. 
  The reason was, apparently that the failing disk had used up the spare 
list:

kernel: sd 0:0:4:0: [sde] Unhandled sense code
kernel: sd 0:0:4:0: [sde] Result: hostbyte=DID_OK 
driverbyte=DRIVER_SENSE
kernel: sd 0:0:4:0: [sde] Sense Key : Hardware Error [current]
kernel: Info fld=0x1949399
kernel: sd 0:0:4:0: [sde] Add. Sense: No defect spare location available
kernel: sd 0:0:4:0: [sde] CDB: Read(10): 28 00 01 94 93 92 00 00 08 00
kernel: end_request: I/O error, dev sde, sector 26514329

That was the last thing in the system log, time stamped at a point that 
should have been roughly the end point of a full long SMART test.

This was quite an old kernel, 2.6.34.9.

So, as I said above, I'm not 100% sure that this failing disk wasn't 
mounted.  If it was, the mount point would have been /tmp/sde, which 
isn't a path anything on the system would have cause to look into.

Does the "no defect spare location available" error really cause a 
system crash when it happens on a disk that isn't mounted, or must a 
disk be mounted for this sort of error to crash the system?

Regards,

David Mathog
[email protected]
Manager, Sequence Analysis Facility, Biology Division, Caltech

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