How Many Sectors Can Fail Before Hard Drive Fails? What To Do?

djfunz

Limp Gawd
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Apr 2, 2007
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Hi guys, I'm having a bit of a dilemma deciding what to do with my External Western Digital 1.5 TB Hard Drive. I've had it over a year and suddenly with iTunes it randomly freezes while I'm listing to music. I have no idea why but only with iTunes. Anyway I decided to run an overnight HD Tune error scan on it and it came up with 7 bad sectors on it. The (C5) Current Pending Sector section under the health tab also lists the 7 bad sectors. Each sector has 572MB on it so it adds up to be a large chunk of data. It holds my music collection of several years, so I don't want to take a risk with it. I read around and it seems to be a mixed bag of opinions. Some say replace immediately and others say they've had bad sectors for years and it still works fine. For safety I backed up the data on another old Seagate external drive and that one has bad sectors too!! Is this really something to worry about or are these readings more hot smoke than anything else to get people scared into buying new drives? I lost my box but still have my receipt so I'm not sure what to do. How many sectors can go bad until the whole drive stops working? Thanks for the insight everyone.
 
It's a Western Digital drive, you should be using Western Digital's DataLifeguard Tools diagnostic for testing purposes and nothing else. Go get that, let it have at the drive and see what it reports. Obviously, do a quick/short scan first and regardless of the results (meaning if it comes back completely "OK" from the quick/short scan) run the advanced/thorough one as well. That one will take a significant chunk of time on a 1.5TB drive, especially if it's using USB.

But that's the tool to use. I'm pretty sure that drive would still be under warranty, and if it is, the results of that diagnostic will provide a status code that WD would require if you try to get a warranty replacement. The DataLifeguard Tools will tell you if it's a shot drive, as well, which would give you ground to stand on in making the warranty claim and getting the RMA.

But, whenever you have a hard drive that's questionable in terms of potential errors, use the diagnostic software provided by the drive's manufacturer as the tool for doing the testing - if you have a drive built by some company that doesn't provide such a tool (rare but it happens), you can use the Hitachi Drive Fitness Test as it's not a brand-locked or brand-specific testing tool and can be used with any hard drive.

Good luck...

Just for the record: a sector on an NTFS formatted drive (which I'm sure that drive is using as the file system) is 4096 bytes, or 4KB, so 7 of 'em ain't gonna total 4GB (7 x 572MB = 4004MB aka 4GB). Not sure where that number is coming from, the 572MB figure, but 7 bad sectors out of billions ain't that bad really. I'm suspecting there's something else wrong with the drive.

Just for the record 2: I've had a lot of people bring me WD external drives in the past year that were simply pieces of shit. I just did some attempted data recovery off a WD 500GB MyBook last weekend and was unsuccessful because the drive was mechanically unsound and couldn't be recognized by the BIOS when directly attached nor seen by any OS when using the USB connection. Complete pieces of shit... might think about trying Seagate externals next time - just a suggestion, but I've never had a client bring me one that's going bad or already dead. At least, not yet. :p
 
I actually ran into problems with one of my WD20EARS last weekend. I used the Datalifeguard Quick Test which came back as 'PASS' though I knew something was wrong because it took 10 minutes to scan instead of thee normal 2 minutes. I did the extended test which took about 6 hours on SATA II connection so it'll probably be pretty long for your 1.5 external USB. It found bad sectors and attempted to fix but was unable so I'm in the process of RMA.

You say you still have the receipt, is it eligible for return/exchange from where ever you bought it? Otherwise just do a RMA through Western Digital, you can do the advance RMA where they send you a replacement first so you can copy your files before sending the defective drive.

But, whenever you have a hard drive that's questionable in terms of potential errors, use the diagnostic software provided by the drive's manufacturer as the tool for doing the testing - if you have a drive built by some company that doesn't provide such a tool (rare but it happens), you can use the Hitachi Drive Fitness Test as it's not a brand-locked or brand-specific testing tool and can be used with any hard drive.

Isn't the Datalifeguard Tools also not brand-locked? I've used it on Hitachi and Samsung drives, though maybe it's not as good as the manufacturer specific one?
 
In the olden days of IDE (or even proprietary) drive interfaces you absolutely needed to stick to the manufacturers tools. In those days, that was good advice.

However, with SATA drives all the 'tools' do is kick off a SATA-standard built in self test (BIST) command on the drive. It is either the SATA quick test or the SATA long self test, but it is a standard test kicked off by a standard command. It does not really matter whose software you use to kick it off.

If the self-test fails, you might need to use the vendor's software to properly interpret the error codes and to get the right RMA code. Those remain vendor specific.
 
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Isn't the Datalifeguard Tools also not brand-locked? I've used it on Hitachi and Samsung drives, though maybe it's not as good as the manufacturer specific one?

I've never tested the WD tool for being brand-locked; the suggestion for always using the like manufacturer's tool for their own branded drives is because they will typically give a status code that relates specifically to that brand, a disposition code that doesn't apply to anything else. Example: if you have an actual Hitachi drive that's going bad and fails the Hitachi DFT, it'll give you a disposition/status code that you have to provide to get the RMA from Hitachi. Without that code, you'll have a really tough time doing a return unless the drive is flat out toast and can't even run the DFT in the first place.

I know WD's DataLifeguard Tools is capable of providing such a code for their own drives, so is Seagate's tool for it's own brand of drives (and Maxtors too). So that's where the recommendation to always use the manufacturer's diagnostic for any given brand of drive comes from.

Duh, noted the post above says pretty much the same thing about the disposition codes... :D
 
Generally you should have few or mostly NO bad sectors on a hard drive. The fact that you got seven is not too bad, unless they all appeared suddenly.

I would check it again in a few days and see if it is getting worse.

What gives me concern is the random freezing. That is a sign that the drive is encountering errors and attempting to repair them or move data to a spare sector. Again, not in itself fatal, but not a good sign for the long term health of your drive.

The most important thing to remember though is that any hard drive can fail suddenly and catastrophically at ANY time. You do have at least 1, preferably 2 or more copies of ALL of your important data, don't you?

Don
 
Agreed with the post above, and I forgot to comment on that aspect even though the OP did mention it: random hard lockups, the kind where the whole computer just kinda "stop" for several seconds, sometimes longer, and you see the hard drive activity light (if you have one, some folks cover 'em up nowadays) staying on steadily, that's a drive getting ready to crap out and die on ya... sorry I missed that but, Don covered it in his post above.

And I do believe either today or tomorrow (Friday) is "World Backup Day" so... back that shit up, folks. :D
 
I think that the drive is starting to show more signs of wear as the days progress. I tried the diagnostic tools from WD and the quick test displayed that everything was ok. The complete and through test would take 16 hours and I would rather just replace the drive at this point. My general question however still remains. How Many Sectors Can Fail Before Hard Drive Fails? How many are preallocated as "spare"?

The WD Elements Drives also only have a 2 year warranty on them which makes me wonder how good their quality actually is. Odd though, because I thought all platter drives were built on a basic and consistent process. Why do the Western Digital My Passport Elite drives for instance, have a 5 year warranty? That's a big difference!

My goal now is to just replace the drive as quick as possible and hope my other 6 year old Seagate External Drive holds out long enough to copy the data back to the soon to be replaced Drive. *crossing fingers*



Just for the record 2: I've had a lot of people bring me WD external drives in the past year that were simply pieces of shit. I just did some attempted data recovery off a WD 500GB MyBook last weekend and was unsuccessful because the drive was mechanically unsound and couldn't be recognized by the BIOS when directly attached nor seen by any OS when using the USB connection. Complete pieces of shit... might think about trying Seagate externals next time - just a suggestion, but I've never had a client bring me one that's going bad or already dead. At least, not yet. :p

Interesting that you say that because I've had problems with both manufactures, however a little after a year is odd to me. I was also always a fan of Seagate and I think the WD Green drives were just cheaper per GB. I would like to see some type of documentation suggesting the manufacturing process is different between Seagate drives and WD drives.
 
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About the sector / 572MB confusion it's because HD Tune shows the disk as little green or red squares of a size depending on the total size of the disk. If it finds an error the block where it found it will go red, but it doesn't mean all 572MB of data are bad, it's just so you have a global picture at the end. It should give the exact number of errors found (I'm not sure, long time without a red block).

This is NOT the same as reallocated sectors, by the way. During normal use of the drive, if a sector is found as defective, the drive will take care of it, that's what is displayed in the SMART. If you scan the drive with HDTune, it should be all green, regardless of the number of reallocated sectors.

Personally, at the first red block, I RMA the drive.
 
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