fixing hard drive errors with WD Diags

[techidave]

I have a question about Western Digital Diagnostics testing procedure.  If I run the extended test, it first runs the quick test.  It found a read error of -23 (or maybe a -3) but i don't remember for sure.  It then asked if I wanted to go ahead with the extended test and I said yes.  At the end it said it had fixed the problem but didn't ask me if I wanted to fix the problem it just went ahead and did it.

Should I trust that it did fix it??   This  was a WD300BB drive made back in 2001.  I went and rested the drive and it didn't find any errors.

I am not sure about putting this  back in the classroom and then having to redo it again a month for now.   

This is the first time I have had the diags fix a problem so I am a little hesitant if it will run for a long time or not.

Dave

[mwb1100]

Chances are that the diagnostic simply 'mapped' the bad sector to a spare sector that has been set aside for that purpose.

If you're not confident in the stability of the drive you could try running an alternate diagnostic that does a surface scan or maybe just replace the drive (it's getting long in the tooth anyway) - you can get a drive that's considerably larger than 30GB for as little as $50.

It all depends on whether you want to spend time or money to get your confidence in the drive back (or just take wddiag's word for it).

[tinjaw]

Having run the WD diagnostic tools for about 30 hours these past three or four days (I kid you not) I can confirm that it indeed did just map bad sectors to spare sectors. You should be just fine.

[techidave]

I think I will let it go back to the classroom as it and see what happens.  I could run Spinrite on it but it takes so long to complete.  I could wait and run it over the weekend to see how it does.

Dave

[f0dder]

Friends don't let friends get fooled by the spinrite snake oil...

All drives manufactured the last many years have had a pool of spare sectors that bad sectors can be remapped to. The catch, however, is that this is only done on write to the sector, not read... so traditional systems like NTFS will detect the bad sector and map it as bad in the filesystem metadata structures, and won't try to read the sector again.

Then comes half-educated power-user that's been charmed by the GibsonGibberish^TM about magic bitpatterns and magnetic surface scrubbing, and is amaaaaazed when Spinrite magically repairs the disk omfg!. And what does spinrite do? It tries to read and re-write the sector a lot of times. This will usually result in the drive reallocating the sector (check your drive's Rellocated Sector Count S.MA.R.T property), and "fix" the problem... but ask your self what kind of stress continually trying to access a bad sector puts on the drive.

I wouldn't use spinrite on a dying drive before I had made an image of all the readable sectors, simply because the drive might very well die in the process of spinriteing it. And I hate how the guy is getting away with pushing his snake oil simply because he's paid convinced a number of prominent names to praise it. And he makes it sound like it's hard to program in assembly, heh.

[techidave]

Whoa!  Sounds like I touched a nerve with fodder about Spinrite.   But lets not get into badmouthing others, ok.  The good thing about this particular hard drive is it's a classroom computer used by students, I can just re-ghost it and it will be up and running in short order.

[f0dder]

Whoa!  Sounds like I touched a nerve with fodder about Spinrite.   But lets not get into badmouthing others, ok.

-techidave (February 25, 2008, 08:07 PM)

Yes, you struck a nerve - I have a real big dislike for false prophets, and I don't want anybody to face a complete drive trashing due to spinrite stress...

[techidave]

Ok so this brings another question.  How does what Spinrite does differ than what WD Diags or anyone's elses do??  Hope you can understand that last question.  <grin>

[f0dder]

Ok so this brings another question.  How does what Spinrite does differ than what WD Diags or anyone's elses do??  Hope you can understand that last question.  <grin>

-techidave (February 25, 2008, 08:38 PM)

This is a very good question, and one I can't answer - simply because Gibson doesn't provide any hard facts, only mumbo-jumbo about magical bit patterns and whatnot. Oh, and spinrite has pretty text-mode graphics including animated sine curves... it does give you an impression it's doing something really profound, doesn't it? Personally I prefer hard facts, rather than tv-shop style circle-jerk praise emails

But I'll leave the topic, the people who have had data "saved by spinrite" will obviously claim that it does something magical that other tools can't. Like, setting retrycount=infinity

[techidave]

maybe that is why he has never gotten around to writing a new manual??  Personally, I never understood his mumbo jumbo and actually haven't used the program for a year or two since I could never really verify it did much. 

Looks like trying the mfg's software may be the best way to go when a drive is going bad.  Since we are a small public school in the USA, money is always tight. 

During the summer when I usually run MemTest and reghost each student machine, I may have to add the mfg's diagnostic test to this project.  Maybe it will save some headaches as the new school year progress.

[f0dder]

maybe that is why he has never gotten around to writing a new manual??  Personally, I never understood his mumbo jumbo and actually haven't used the program for a year or two since I could never really verify it did much.

-techidave (February 25, 2008, 09:39 PM)

Well, to be honest I can't rule out that it does something more than just re-allocating bad sectors. I think his claim is that he "scrubs the sectors with magic bit-patterns to re-magnetize the surface" or something, but I fail to see how that would work - especially since a write to a bad sector triggers reallocation (but OK, perhaps it's possible to turn that feature off temporarily).

Afaik SpinRite hasn't been updated since 6.0 was released (some time during 2004?), but appearantly it's an effective cash cow. Probably helps a lot with all those positive reviews the "reputable sources" give, it's a self-enhancing mass delusion

Looks like trying the mfg's software may be the best way to go when a drive is going bad.  Since we are a small public school in the USA, money is always tight.

-techidave (February 25, 2008, 09:39 PM)

That's what I would do. And as soon as a drive starts getting re-allocated sectors, I rescue all data and consider the drive as dead; I might use it for transferring non-critical data or as a scratchpad, but not for anything important. I've had drives work like that for years... and I've had them fail a few weeks the first re-allocated sector. Thinking that you have repaired a drive with spinrite (or anything else) is outright dangerous.

During the summer when I usually run MemTest and reghost each student machine, I may have to add the mfg's diagnostic test to this project.  Maybe it will save some headaches as the new school year progress.

-techidave (February 25, 2008, 09:39 PM)

It would probably be a good idea to find a S.M.A.R.T diagnostics tool that can send email reports, and have it trigger on a non-zero reallocated sector count. That'll let you visit potential troublesome machines before things get really bad. If you have routine checks with memtest etc, it's probably not a bad idea adding a disk-vendor-tool full check, just keep in mind that the check itself does put some stress on the system.

[techidave]

Can you recommend a good S.M.A.R.T diagnostics tool that is inexpensive or free.  I believe this would be a good thing to have since my 250 machines are spread out over 3 buildings in 3 different towns and are 7-12 miles apart from the town in the center.   

[f0dder]

Alas, no!

But there's a lot of SMART tools around, and a lot of them are free... so hopefully it's possible to find something that can send email reports. If not, it miiiight be possible to find some open-source code and then it'd be relatively easy to add some report/mailing stuff I reckon. Major problem is that SMART info is somewhat weird and can be interpreted in various ways... I think that the re-allocated sector count is relatively sane and interpretable compared to some of the other counts, though