It does appear that different manufacturers use SMART values for sometimes radically different things, as you can see here:
My hard disk(s) in ReadyNAS is reporting high SMART Raw Read Error Rate, Seek Error Rate, and Hardware ECC Recovered. What should I do?
Seagate uses these SMART fields for internal counts, so this is a known issue with Seagate disks. Look for abnormal counts in other fields, especially Reallocated Sector Ct and ATA Error Count.
So when it comes to your actual question …
If I am lucky enough for a bad drive to show a hint of failure such as scan errors or reallocated sectors, I know to get the drive the heck out of there. If no such hint exists, I’ll probably spend many hours troubleshooting slowness and data corruption until I finally find that the hard drive is bad.
I’d say a good rule of thumb is, you can only expect SMART settings to be comparable within the same drive manufacturer, and maybe even the same drive model!
So when you’re looking at diagnosing those SMART counts, keep that in mind… one manufacturer’s “read error retry count” may mean something totally different than another manufacturer’s. Sad but true. 🙁
Okay, first of all I disagree with your premise.
Google did a study that indicates that
certain raw data attributes that the
S.M.A.R.T status of hard drives
reports can have a strong correlation
with the future failure of the drive.
In fact they found the opposite:
…we find that failure prediction models
based on SMART parameters alone are
likely to be severely limited in their
prediction accuracy, given that a
large fraction of our failed drives
have shown no SMART error signals
Secondly, SMART thresholds are not standardised. The firmware on the drive itself will flag an attribute as being “pre-failure”, but the raw values are meaningless to the user. For example, Seagate says:
Various attributes are being monitored
and measured against certain threshold
limits. If any one attribute exceeds a
threshold then a general SMART Status
test will change from Pass to Fail.
The SMART values that might be read
out by third-party SMART software are
not based on how the values may be
used within the Seagate hard drives.
Seagate does not provide support for
software programs that claim to read
individual SMART attributes and
thresholds. There may be some
historical correctness on older
drives, but new drives, no doubt, will
have incorporated newer solutions,
attributes and thresholds.
Raw SMART values are almost meaningless, as different manufacturers use them in different ways and have different thresholds etc. The drive firmware itself will tell you when it is in “pre-failure”… or it might not, SMART really isn’t very reliable.
Do regular backups!
I’m not exactly sure what the question is that you’re asking. You seem to have the whole question and answer rolled up into one but…
Have you compared the hard drive metrics to those given from SeaTools
It’s Seagate’s standard hardware diagnostic tool and AFAIK the most commonly used HDD diagnostic tool.
Don’t be surprised if you find that the tools report unfavourable results about their competitors. The tools generally work with HDDs of all manufacturers but that doesn’t mean that they have make their competitors look good while doing.
Haven’t you ever heard the joke, “99.99% of all statistics are true except, of course, this statistic”.
In the physical reality of hard drive internals, all brands of hard drives larger than 100MB will have a lot of physical read errors. Most of those are safely corrected by ECC, some (hopefully very few) are wrongly corrected by ECC and the rest (few but more than the wrong corrections) are reported back to the computer as failed read and should also make the drive automatically relocate the bad sector.
In addition to correcting raw read errors, ECC also corrects reads that the hardware thought were OK, but the returned bits were slightly wrong. Thus ECC corrected might be “raw read failed but fixed by ECC + raw read succeeded but was wrong and got fixed by ECC”.
Thus two interpretations of the data seem possible:
A. non-Seagate drives do not include the ECC corrected read errors in the “raw read error count”, only the unfixable errors.
B. Seagate considers it a read error if ECC finds something wrong with the data even if the low level circuit did not notice, others don’t.
Normalization will be very different depending on which theory (A or B) is right.