Help Diagnose Slow Disc Access

[Mike McCarty]

Don Quixote de la Mancha wrote:
> All of the hard drive vendors provide disk drive diagnostic tools,
> that are able to access vendor-specific - and undocumented - firmware
> in their drives.  This diagnostic firmware is able to diagnose drive
> hardware problems in a much more thorough way than the vendor-neutral
> S.M.A.R.T. is able to.

Ok, AFAICT, the WD diagnostic disc simply used the S.M.A.R.T.
conveyance test, which it aborted. Timing aside, that disc passes
all the tests that smartctl knows about.

SMART Error Log Version: 1
No Errors Logged

SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining 
LifeTime(hours)  LBA_of_first_error
# 1  Conveyance offline  Completed without error       00%     12146 
      -
# 2  Extended offline    Completed without error       00%     12107 
      -
# 3  Short offline       Completed without error       00%     12009 
      -

I've noticed that top often reports 50% or more hi (hardware interrupt)
when the system is slow, and that drive is being hit. I just did a copy
from that disc to another of a 90MB or so ISO and saw 95.4% hi.

This seems to imply that the disc is signalling completion, and the
controller is generating an interrupt, but then the handler is having
to poll for a while before getting the go ahead from the disc. Is
this normal?

Mike
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