[Maybe OT] What causes "bad blocks" to appear in disk drives
 

Hello people.

I have an oldish 800MB hard drive here which is still working (it stores some
audio files).

Recently, after a power surge, it developed a "bad block" (4kb marked as bad),
but it still works correctly.

Q: What is a "bad block" in a hard drive?
Physical damage?

Thanks
--
Chaos Master®, posting from Brazil. REPLY TO GROUP!
"People told me I can't dress like a fairy.
I say, I'm in a rock band and I can do what the hell I want!"
-- Amy Lee

Note: please don't give me TinyURL addresses.

Hi!

Recently, after a power surge, it developed a "bad block" (4kb marked as
bad),
but it still works correctly.
Q: What is a "bad block" in a hard drive?
Physical damage?

Usually, yes. It is not really possible to manufacture a truly "perfect"
hard disk even today. Onboard controllers have become smarter and with
automatic defect relocation schemes drives appear to be defect free deal, at
least in the onset. Over time, as the media inside wears down additional bad
spots can develop.

Advanced disk repair utilities (like the GRC tool, SpinRite, at
http://grc.com/) can sometimes convince the drive's electronics to replace
the bad spot with a good spare.

Sometimes these spots start to spread like wildfire and the drive is soon
rendered unreliable. Other times (much more common) the drive simply
develops a little defect for no readily apparent reason. I have a few like
this that have been running for years and no further defects or bad spots
have appeared.

I've also had at least one 2.1GB Western Digital that was almost totally bad
as per Scandisk yet it still managed to hang on long enough to copy all of
its data with only one lost file! That operation took all night with the
drive making bad "retry" sounds, but when I put in the replacement drive and
placed all the files back on it, the system and its OS were no worse for the
wear. I was amazed...that was the only time I've ever seen that happen.

Basically, keep an eye on your drive. Back up the contents and run a disk
utility every now and then. If the drive seems OK, don't let your guard
totally down...just continue to keep an eye on it and if you see things
start to get worse--get the data off immediately (hard disk drives don't
usually give out as many warnings as the WD unit above...) and get a new
drive.

Note: please don't give me TinyURL addresses.

I don't use that service, and have never tried it, but why not?

William

William R. Walsh whispers:
Hi!

Recently, after a power surge, it developed a "bad block" (4kb marked as
bad),
but it still works correctly.
Q: What is a "bad block" in a hard drive?
Physical damage?

Usually, yes. It is not really possible to manufacture a truly "perfect"
hard disk even today. Onboard controllers have become smarter and with
automatic defect relocation schemes drives appear to be defect free deal, at
least in the onset. Over time, as the media inside wears down additional bad
spots can develop.
[... explanations about bad blocks ...]

Thank you for the info.
This helps me.

Note: please don't give me TinyURL addresses.

I don't use that service, and have never tried it, but why not?

I am getting lots of spam/porn "hidden" as TinyURL links (e.g.
http://www.mycrappypornsite.com - http://tinyurl.com/foobar )

[]s
--
Chaos Master®, | "My wounds cry for the grave,
posting from | my soul cries for deliverance.
Brazil. | Will I be denied Christ,
REPLY TO GROUP!| tourniquet, my suicide?" - Evanescence

On Sat, 4 Sep 2004 00:17:31 -0300, Chaos Master
wrote:

Hello people.

I have an oldish 800MB hard drive here which is still working (it stores some
audio files).

Recently, after a power surge, it developed a "bad block" (4kb marked as bad),
but it still works correctly.

Q: What is a "bad block" in a hard drive?
Physical damage?

Thanks


If you're worried about the drive, go to the manufacturer's web site
and download their diagnostic utility. It will test the entire drive
and tell you if there's anything wrong with it. It may even be able
to repair the bad sector. I always do this to a drive, even if it's
new. You'd be surprised how many drives seem fine, but fail to meet
factory specs.
Andy Cuffe

Chaos Master wrote:

I have an oldish 800MB hard drive here which is still working (it
stores some audio files).

Recently, after a power surge, it developed a "bad block" (4kb
marked as bad), but it still works correctly.

Q: What is a "bad block" in a hard drive?
Physical damage?

Not necessarily. Data is stored in sectors, each of which is
preceded by an identification block. The data in both the sector
proper and the identification block are normally protected by
CRCs, to detect any errors. Your power surge could have induced
something in the heads while passing over those areas and
corrupted them. If in the data section the error will go away
after writing new data there. If in the identification block the
sector is lost, because modern drives have no user available
method of low level formatting.

However all drives fail. The only question is when. So, keep
backups if you value your data.

--
Chuck F ) )
Available for consulting/temporary embedded and systems.
http://cbfalconer.home.att.net USE worldnet address!

"William R. Walsh" m pí¹e
v diskusním pøíspìvku news:qPa_c.114343$Fg5.80131@attbi_s53...
Hi!

Recently, after a power surge, it developed a "bad block" (4kb marked as
bad),
but it still works correctly.
Q: What is a "bad block" in a hard drive?
Physical damage?

Usually, yes. It is not really possible to manufacture a truly "perfect"
hard disk even today. Onboard controllers have become smarter and with
automatic defect relocation schemes drives appear to be defect free deal,
at
least in the onset. Over time, as the media inside wears down additional
bad
spots can develop.

Advanced disk repair utilities (like the GRC tool, SpinRite, at
http://grc.com/) can sometimes convince the drive's electronics to replace
the bad spot with a good spare.

Sometimes these spots start to spread like wildfire and the drive is soon
rendered unreliable. Other times (much more common) the drive simply
develops a little defect for no readily apparent reason. I have a few like
this that have been running for years and no further defects or bad spots
have appeared.

I've also had at least one 2.1GB Western Digital that was almost totally
bad
as per Scandisk yet it still managed to hang on long enough to copy all of
its data with only one lost file! That operation took all night with the
drive making bad "retry" sounds, but when I put in the replacement drive
and
placed all the files back on it, the system and its OS were no worse for
the
wear. I was amazed...that was the only time I've ever seen that happen.


I have similiar experience.
I had an 40GB IBM drive. There were sometimes random problems - some files
couldnt be read, drive couldnt boot, clicking sounds were heard. After
reformatting the HDD there were no bad sectors, but in a week, problems were
back again... the drive was really unreliable.
So I sent it back to store and they gave me new (Maxtor) and its OK now...

Zdenek Sojka

) whispers:

Not necessarily. Data is stored in sectors, each of which is
preceded by an identification block. The data in both the sector
proper and the identification block are normally protected by
CRCs, to detect any errors. Your power surge could have induced
something in the heads while passing over those areas and
corrupted them. If in the data section the error will go away
after writing new data there. If in the identification block the
sector is lost, because modern drives have no user available
method of low level formatting.

OK, Thanks.

However all drives fail. The only question is when. So, keep
backups if you value your data.

I have backup, but since it's mainly rare MP3 files, the problem would be
downloading them again.

Thanks for all that helped!
--
Chaos Master®, posting from Brazil. REPLY TO GROUP!
"People told me I can't dress like a fairy.
I say, I'm in a rock band and I can do what the hell I want!"
-- Amy Lee


Outgoing messages are certified virus-free.
They're plain text, anyway.

You oughtta get Norton Ghost and simply clone the drive. Might as well go to a
bigger one as well, I recently bought a Maxtor 6Y08OLO for $62, which is a very
fast and quiet drive. Eighty gigs and I got it half full already. I couldn't
imagine even getting by on a 40 gig, let alone less.

If those MP3s are indeed rare they should be burned to CD. Incedentally, just
what kind of MP3s you got that are so rare ? I collect such things and you've
piqued my curiousity.

JURB

When a read/write head crashes into the spinning disk because of power
interuptions or jarring, particles break loose and cause parts of the drive
to become unreadable. These particles could move around if the drive was
jarred or the drive position was changed. This used to be a very common
problem in early hard drives but modern drives have largely eliminated this
problem.


"Andy Cuffe" wrote in message
...
On Sat, 4 Sep 2004 00:17:31 -0300, Chaos Master
wrote:

Hello people.

I have an oldish 800MB hard drive here which is still working (it stores
some
audio files).

Recently, after a power surge, it developed a "bad block" (4kb marked as
bad),
but it still works correctly.

Q: What is a "bad block" in a hard drive?
Physical damage?

Thanks


If you're worried about the drive, go to the manufacturer's web site
and download their diagnostic utility. It will test the entire drive
and tell you if there's anything wrong with it. It may even be able
to repair the bad sector. I always do this to a drive, even if it's
new. You'd be surprised how many drives seem fine, but fail to meet
factory specs.
Andy Cuffe