Thanks for the update. I suspect this is probably due to buggy SMART
firmware on the disk. When writing and reviewing disk firmware, the
disk vendors seem to be mostly concerned with performance (read/write
speed) since this is what gets tested by reviewers and is used by
customers in determining what to buy. The SMART part of the firmware is
often an afterthought, and is not written or reviewed with the same
attention to detail.
David Mathog wrote:
> Summary so far: some old Seagate ST340016A disks were found to have
> nonzero 'Offline uncorrectable' and 'Current_Pending_Sector' counts
> which could not be reset to zero by writing to every block on the disk.
> I contacted Seagate about this issue, and the best I could get out of
> them (on the second attempt) was:
> | I understand you are getting unclearable SMART 197 and 198
> | fields on your drive. We do not recommend tampering with your
> | SMART values on the drive in any way. We do not have any utility
> | ourselves for clearing these fields. Seatools is the only valid
> | diagnostic that we use to test the drives for functionality. If
> | the drive passes both the short and long test of Seatools then
> | the drive itself is fine. If it fails the tests then the drive
> | should be replaced.
> I did not want to "tamper" with the drives, I just asked if there was a
> way to clear these fields. (Neither seatools nor dd will do so.)
> Anyway, no answer on why these particular drives ended up with these
> counts "stuck". The disks all pass both the long and short SMART tests.
> I suspect that this is related to the disks having been powered off for
> a very long time, well over a year. I think maybe that if the counts
> are set in these two fields, and the disks are left off for a very long
> time, somehow or other the firmware loses track of them. For instance,
> it may associate a time field with these blocks, and allow only so long
> (6 months?) before it swaps them out even if they are not overwritten,
> neglecting to clear the two fields when it does so. So when the disks
> were powered back up, this check may have been performed, resulting in
> the observed "stuck" values in those fields. Whatever this issue is,
> according to Seagate, it apparently does not indicate a failing disk.
> David Mathog
> Manager, Sequence Analysis Facility, Biology Division, Caltech