slightly off topic: SMART error values for seagate drives
quartz at sneakertech.com
Fri Jul 3 02:08:24 UTC 2015
Is anyone familiar with exactly how the raw_read_error_rate,
reallocated_sector_count, seek_error_rate, hardware_crc_recovered, and
udma_crc_error_count values work for seagate drives?
AFAIK at least some of these fields list the (average?) number of
sectors between errors, and thus a higher raw value is better ...I
think. I have several apparently healthy seagate drives with very high
rrer/ser/her raw values that seem to support this.
I recently took an older disk out of storage, and as part of my system
building procedure I always run a few tests over it before putting it
back into service. Initially it also had high rrer/ser/her raw values.
It failed a SMART extended test at about 40% remaining with a read
failure, and the udma_crc_error_count jumped from 0 to 5. I know
sometimes this can be just transient flakiness, so I just zeroed out the
entire drive with dd to exercise all the sectors and force any
remappings. Now, the reallocated_sector_count bumped up to 9, and the
raw_read_error_rate and hardware_crc_recovered fields plummeted from the
millions down to like 13 ...and have since slowly risen to the 40's.
I can't tell what's going on with SMART values anymore, every vendor
does things differently and nothing's ever documented. Is having the
reallocated sectors value go up still a bad thing, or did seagate change
what this means? Why did the read error rate and crc recovered fields
bottom out, but the seek error rate is still in the clouds? Is this
drive failing, or fine, or what?
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