More life from hard disk with bad sectors

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

Hi All

One of my hard disks continued to develop bad sectors and every time I
was using format to mark the bad sectors. Suddenly I got an idea of
not only marking the bad sector but also keeping the head from
accessing areas around the bad sector.

By the time I did this to my hard disks it had only 1 gb of its 2 gb
capacity usable. (You can imagine the number of bad sectors!).

The bad sectors developed during a three month period. After marking
the areas so the read head did not go anywhere near the bad sectors I
have been using this hard disk for more than two years without any new
bad sector appearing!

You can read my experience here

http://members.tripod.com/~diligent/ninelives.htm

HTH

--
Sandy Archer
Reply to newsgroups only

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

"Ardent" <iam@here.com> wrote in message
news:5bi7g09uho70vvl04krriamdgltl23jeic@4ax.com...
> Hi All
>
> One of my hard disks continued to develop bad sectors and every time I

As soon as a HD begins to develop more than a very few bad sectors then
assume the HD is DOA as the rest will go bad soon. Replace the HD. We'll
keep your post as perfect proof of this point.

> was using format to mark the bad sectors. Suddenly I got an idea of
> not only marking the bad sector but also keeping the head from
> accessing areas around the bad sector.
>
> By the time I did this to my hard disks it had only 1 gb of its 2 gb
> capacity usable. (You can imagine the number of bad sectors!).
>
> The bad sectors developed during a three month period. After marking
> the areas so the read head did not go anywhere near the bad sectors I
> have been using this hard disk for more than two years without any new
> bad sector appearing!
>
> You can read my experience here
>
> http://members.tripod.com/~diligent/ninelives.htm
>
> HTH
>
> --
> Sandy Archer
> Reply to newsgroups only

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

"Ron Reaugh" <ron-reaugh@worldnet.att.net> wrote in
news:NCZMc.325853$Gx4.193789@bgtnsc04-news.ops.worldnet.att.net:

> As soon as a HD begins to develop more than a very few bad sectors
> then assume the HD is DOA as the rest will go bad soon. Replace the
> HD. We'll keep your post as perfect proof of this point.

I consider anything > 0 bad sectors as meaning "The drive is dying,
immediately replace it"

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

Nonsense. Your drive had bad sectors when it was shipped.

"Jim Berwick" <jimb@snip.net> wrote in message
news:Xns953213B4820A8jimbsnipnet@207.103.26.26...
>
> I consider anything > 0 bad sectors as meaning "The drive is dying,
> immediately replace it"

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

lol, back in the old days (286, 386) harddrives weren't cheap so when an hd
developed bad sectors, the bad sector areas was partitioned off and never
used again

"Ardent" <iam@here.com> wrote in message
news:5bi7g09uho70vvl04krriamdgltl23jeic@4ax.com...
> Hi All
>
> One of my hard disks continued to develop bad sectors and every time I
> was using format to mark the bad sectors. Suddenly I got an idea of
> not only marking the bad sector but also keeping the head from
> accessing areas around the bad sector.
>
> By the time I did this to my hard disks it had only 1 gb of its 2 gb
> capacity usable. (You can imagine the number of bad sectors!).
>
> The bad sectors developed during a three month period. After marking
> the areas so the read head did not go anywhere near the bad sectors I
> have been using this hard disk for more than two years without any new
> bad sector appearing!
>
> You can read my experience here
>
> http://members.tripod.com/~diligent/ninelives.htm
>
> HTH
>
> --
> Sandy Archer
> Reply to newsgroups only

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

Monster wrote:

> lol, back in the old days (286, 386) harddrives weren't cheap so when an
> hd developed bad sectors, the bad sector areas was partitioned off and
> never used again

Still are. But it's handled transparently by drive now. When an IDE drive
is showing bad sectors it generally means that it's got more than the
onboard sparing can handle, which means that it's _real_ bad.

> "Ardent" <iam@here.com> wrote in message
> news:5bi7g09uho70vvl04krriamdgltl23jeic@4ax.com...
>> Hi All
>>
>> One of my hard disks continued to develop bad sectors and every time I
>> was using format to mark the bad sectors. Suddenly I got an idea of
>> not only marking the bad sector but also keeping the head from
>> accessing areas around the bad sector.
>>
>> By the time I did this to my hard disks it had only 1 gb of its 2 gb
>> capacity usable. (You can imagine the number of bad sectors!).
>>
>> The bad sectors developed during a three month period. After marking
>> the areas so the read head did not go anywhere near the bad sectors I
>> have been using this hard disk for more than two years without any new
>> bad sector appearing!
>>
>> You can read my experience here
>>
>> http://members.tripod.com/~diligent/ninelives.htm
>>
>> HTH
>>
>> --
>> Sandy Archer
>> Reply to newsgroups only

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

"J. Clarke" <jclarke@nospam.invalid> wrote in message
news:ce3db901m73@news2.newsguy.com...
> Monster wrote:
>
> > lol, back in the old days (286, 386) harddrives weren't cheap so when an
> > hd developed bad sectors, the bad sector areas was partitioned off and
> > never used again
>
> Still are. But it's handled transparently by drive now. When an IDE drive
> is showing bad sectors it generally means that it's got more than the
> onboard sparing can handle, which means that it's _real_ bad.
>
There are around 100,000 spares on a 50GB drive. SMART would have said the
drive was toast long before they ran out.

 

[cjt]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

Eric Gisin wrote:

> Nonsense. Your drive had bad sectors when it was shipped.

Not that are visible. By the time you see any, there are really
quite a few. That's different from a few random ones at the time
of manufacture.

>
> "Jim Berwick" <jimb@snip.net> wrote in message
> news:Xns953213B4820A8jimbsnipnet@207.103.26.26...
>
>>I consider anything > 0 bad sectors as meaning "The drive is dying,
>>immediately replace it"
>
>


--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

"CJT" <abujlehc@prodigy.net> wrote in message
news:41052EBE.3010701@prodigy.net...
> Eric Gisin wrote:
>
> > Nonsense. Your drive had bad sectors when it was shipped.
>
> Not that are visible. By the time you see any, there are really
> quite a few. That's different from a few random ones at the time
> of manufacture.
>
There are hundreds of initial bad sectors on each of my three SCSI drives.

It is quite normal to develop a few new ones each year, and that does NOT
indicate the drive is failing. Normally they are not visible, because they are
corrected and remapped.

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

In article <ce3cl503ki@enews3.newsguy.com>,
Eric Gisin <ericgisin@graffiti.net> wrote:
>"CJT" <abujlehc@prodigy.net> wrote in message
>news:41052EBE.3010701@prodigy.net...
>> Eric Gisin wrote:
>>
>> > Nonsense. Your drive had bad sectors when it was shipped.
>>
>> Not that are visible. By the time you see any, there are really
>> quite a few. That's different from a few random ones at the time
>> of manufacture.
>>
>There are hundreds of initial bad sectors on each of my three SCSI drives.
>
>It is quite normal to develop a few new ones each year, and that does NOT
>indicate the drive is failing. Normally they are not visible, because they are
>corrected and remapped.
>


SMART monitering will tell you when if the device is within
manufacturer's tolerances. Everest from Lavalist is a nice package
(free for noncommercial use.) I don't have a link handy.

With XP I've seen an event log entry following a perceptable pause on
my PC. The log showed that a block had just meen remapped.

If I see a single additional block remapped on a machine being used
for revenue-producing business use I plan to swap that disk
out, asap.

I'd mark the disk and use it for some don't-care-if-burns purpose.
The disk doesn't get a third chance.

--
Al Dykes
-----------
adykes at p a n i x . c o m

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

"Ardent" <iam@here.com> wrote in message news:5bi7g09uho70vvl04krriamdgltl23jeic@4ax.com...
> Hi All
>
> One of my hard disks continued to develop bad sectors and every time I
> was using format to mark the bad sectors. Suddenly I got an idea of
> not only marking the bad sector but also keeping the head from
> accessing areas around the bad sector.
>
> By the time I did this to my hard disks it had only 1 gb of its 2 gb
> capacity usable. (You can imagine the number of bad sectors!).
>
> The bad sectors developed during a three month period. After marking
> the areas so the read head did not go anywhere near the bad sectors I
> have been using this hard disk for more than two years without any new
> bad sector appearing!
>
> You can read my experience here
>
> http://members.tripod.com/~diligent/ninelives.htm

Several possible flaws in your method.

1) only works for drives smaller than 8GB

2) no drive has 256 physical heads and 63 sectors per track so
1 logical cylinder is already many physical cylinders
With 4 heads and ~600 sectors/tr. you already reserve ~6
physical cylinders per logical cylinder.

3) it's not the heads that need keeping away from the damaged
spots but the slider that they are mounted on, which is much
wider. The slider can cover into the hundreds of cylinders.

Btw, why not finish the experiment and zero-write the whole
drive and use it as one normally would, and see what happens.

If your theory is correct it should soon die. Somehow, I doubt that.

>
> HTH
>
> --
> Sandy Archer
> Reply to newsgroups only

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

"J. Clarke" <jclarke@nospam.invalid> wrote in message news:ce3db901m73@news2.newsguy.com...
> Monster wrote:
>
> > lol, back in the old days (286, 386) harddrives weren't cheap so when an
> > hd developed bad sectors, the bad sector areas was partitioned off and
> > never used again
>
> Still are.

Nope.

> But it's handled transparently by drive now.

But doesn't reduce its capacity.

> When an IDE drive
> is showing bad sectors it generally means that it's got more than the
> the onboard sparing can handle, which means that it's _real_ bad.

Utterly Clueless.
When an IDE drive is showing bad sectors it generally means that
the "bad" sectors are unrecoverable read error bad sectors and
that the sparing system is incapable of replacing them as bad data
then would reappear as correct data in the replacement sector.

The unrecoverable read error bad sector will disappear nicely after
a write to the so-called "bad" sector.
"When an IDE drive is showing bad sectors it generally means" that
such a write to the 'so-called' "bad" sectors has not yet happened.

Ofcourse "J. Clarke" knows this as it has been explained to him
before but he prefers to troll.

>
> > "Ardent" <iam@here.com> wrote in message news:5bi7g09uho70vvl04krriamdgltl23jeic@4ax.com...
> >> Hi All
> >>
> >> One of my hard disks continued to develop bad sectors and every time I
> >> was using format to mark the bad sectors. Suddenly I got an idea of
> >> not only marking the bad sector but also keeping the head from
> >> accessing areas around the bad sector.
> >>
> >> By the time I did this to my hard disks it had only 1 gb of its 2 gb
> >> capacity usable. (You can imagine the number of bad sectors!).
> >>
> >> The bad sectors developed during a three month period. After marking
> >> the areas so the read head did not go anywhere near the bad sectors I
> >> have been using this hard disk for more than two years without any new
> >> bad sector appearing!
> >>
> >> You can read my experience here
> >>
> >> http://members.tripod.com/~diligent/ninelives.htm
> >>
> >> HTH
> >>
> >> --
> >> Sandy Archer
> >> Reply to newsgroups only
>
> --
> --John
> Reply to jclarke at ae tee tee global dot net
> (was jclarke at eye bee em dot net)

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

"Jim Berwick" <jimb@snip.net> wrote in message news:Xns953213B4820A8jimbsnipnet@207.103.26.26
> "Ron Reaugh" <ron-reaugh@worldnet.att.net> wrote in news:NCZMc.325853$Gx4.193789@bgtnsc04-news.ops.worldnet.att.net:
>
> > As soon as a HD begins to develop more than a very few bad sectors
> > then assume the HD is DOA as the rest will go bad soon. Replace
> > the HD. We'll keep your post as perfect proof of this point.
>
> I consider anything > 0 bad sectors as meaning "The drive is dying,
> immediately replace it"

Well, maybe you should look into your S.M.A.R.T. data then, every hour.
It might be in it's death throws already and you not even know it.

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

On Mon, 26 Jul 2004 08:02:11 -0700, Eric Gisin <ericgisin@graffiti.net> wrote:
>Nonsense. Your drive had bad sectors when it was shipped.

Modern hard drives do bad block forwarding, invisible to the operating
system and thus the end user. If you start actually seeing bad blocks
it means that all the spares have been used and the drive is in the
process of dying a grievous death.

--
Roger Blake
(Subtract 10 for email.)

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

"Roger Blake" <rogblake10@iname10.com> wrote in message
news:slrncgfgpk.las.rogblake10@unix2.netaxs.com...
> Modern hard drives do bad block forwarding, invisible to the operating
> system and thus the end user. If you start actually seeing bad blocks
> it means that all the spares have been used and the drive is in the
> process of dying a grievous death.

I don't think that's quite right based on my understanding. If you're
WRITING to the block when the error is first detected by the drive, then the
reallocation is invisible to the OS. However, if a READ is the first time
the error is detected, then an error is returned to the OS (and it will
"detect" a bad block), but the disk then places that block number in a
pending list and the reallocation isn't done the next time it is written to.
Thus, the OS could see an error before the spares have been exhausted.

This process is described in most detailed data sheets for the drives, and
the 5 or so that I've read seem to follow this general process.

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

Clueless gibberish. Read my and Folkert's reply to J Clarke.

"Roger Blake" <rogblake10@iname10.com> wrote in message
news:slrncgfgpk.las.rogblake10@unix2.netaxs.com...
>
> Modern hard drives do bad block forwarding, invisible to the operating
> system and thus the end user. If you start actually seeing bad blocks
> it means that all the spares have been used and the drive is in the
> process of dying a grievous death.
>

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

Taed Wynnell wrote:

> "Roger Blake" <rogblake10@iname10.com> wrote in message
> news:slrncgfgpk.las.rogblake10@unix2.netaxs.com...
>> Modern hard drives do bad block forwarding, invisible to the operating
>> system and thus the end user. If you start actually seeing bad blocks
>> it means that all the spares have been used and the drive is in the
>> process of dying a grievous death.
>
> I don't think that's quite right based on my understanding. If you're
> WRITING to the block when the error is first detected by the drive, then
> the
> reallocation is invisible to the OS. However, if a READ is the first time
> the error is detected, then an error is returned to the OS (and it will
> "detect" a bad block), but the disk then places that block number in a
> pending list and the reallocation isn't done the next time it is written
> to. Thus, the OS could see an error before the spares have been exhausted.
>
> This process is described in most detailed data sheets for the drives, and
> the 5 or so that I've read seem to follow this general process.

If one is being pedantically correct then yes, it's possible to see bad
sectors before the sparing is exhausted. In the real world if you're
seeing bad sectors on an IDE drive, assume the drive is in the transition
phase between "merely dead" and "sincerely dead".

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

 

[cjt]

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

Taed Wynnell wrote:
> "Roger Blake" <rogblake10@iname10.com> wrote in message
> news:slrncgfgpk.las.rogblake10@unix2.netaxs.com...
>
>>Modern hard drives do bad block forwarding, invisible to the operating
>>system and thus the end user. If you start actually seeing bad blocks
>>it means that all the spares have been used and the drive is in the
>>process of dying a grievous death.
>
>
> I don't think that's quite right based on my understanding. If you're
> WRITING to the block when the error is first detected by the drive, then the
> reallocation is invisible to the OS.

Are you implying drives do a read-after-write check? If not (and I
don't think they do such a check routinely), it seems to me the only
way a drive would ever detect such an error (i.e. upon a write) is
if things are so hosed the drive can't even sync to the write location.

However, if a READ is the first time
> the error is detected, then an error is returned to the OS (and it will
> "detect" a bad block), but the disk then places that block number in a
> pending list and the reallocation isn't done the next time it is written to.
> Thus, the OS could see an error before the spares have been exhausted.
>
> This process is described in most detailed data sheets for the drives, and
> the 5 or so that I've read seem to follow this general process.
>
>


--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.

 

[wizard]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

My experience is that Blake is correct. Bad blocks, once seen, grow like
weeds.

Eric Gisin wrote:
>
> Clueless gibberish. Read my and Folkert's reply to J Clarke.
>
> "Roger Blake" <rogblake10@iname10.com> wrote in message
> news:slrncgfgpk.las.rogblake10@unix2.netaxs.com...
> >
> > Modern hard drives do bad block forwarding, invisible to the operating
> > system and thus the end user. If you start actually seeing bad blocks
> > it means that all the spares have been used and the drive is in the
> > process of dying a grievous death.
> >

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

Many of us have reported seeing bad blocks caused by power problems,
which cease when that is fixed.

The explanation "running out of spare sectors" is absolutely idiotic. It is
not possible to remap that many without getting lots of prior warning.

"Wizard" <mskmywvcaqs@grubx.com> wrote in message
news:4107E535.79B81BA6@grubx.com...
> My experience is that Blake is correct. Bad blocks, once seen, grow like
> weeds.
>
> Eric Gisin wrote:
> >
> > Clueless gibberish. Read my and Folkert's reply to J Clarke.
> >
> > "Roger Blake" <rogblake10@iname10.com> wrote in message
> > news:slrncgfgpk.las.rogblake10@unix2.netaxs.com...
> > >
> > > Modern hard drives do bad block forwarding, invisible to the operating
> > > system and thus the end user. If you start actually seeing bad blocks
> > > it means that all the spares have been used and the drive is in the
> > > process of dying a grievous death.
> > >

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

In article <4107D808.1090703@prodigy.net>, CJT <abujlehc@prodigy.net> wrote:
>Taed Wynnell wrote:
>> "Roger Blake" <rogblake10@iname10.com> wrote in message
>> news:slrncgfgpk.las.rogblake10@unix2.netaxs.com...
>>
>>>Modern hard drives do bad block forwarding, invisible to the operating
>>>system and thus the end user. If you start actually seeing bad blocks
>>>it means that all the spares have been used and the drive is in the
>>>process of dying a grievous death.
>>
>>
>> I don't think that's quite right based on my understanding. If you're
>> WRITING to the block when the error is first detected by the drive, then the
>> reallocation is invisible to the OS.
>
>Are you implying drives do a read-after-write check? If not (and I
>don't think they do such a check routinely), it seems to me the only
>way a drive would ever detect such an error (i.e. upon a write) is
>if things are so hosed the drive can't even sync to the write location.
>
>However, if a READ is the first time
>> the error is detected, then an error is returned to the OS (and it will
>> "detect" a bad block), but the disk then places that block number in a
>> pending list and the reallocation isn't done the next time it is written to.
>> Thus, the OS could see an error before the spares have been exhausted.
>>
>> This process is described in most detailed data sheets for the drives, and
>> the 5 or so that I've read seem to follow this general process.
>>
>>
>


Modern Disks have a huge percentage of the raw capacity decicated to
ECC (error correction codes) which is enough redundant data so that if
a block is unreadable the ECC codes will allow the data to be
recalculated and nothing is lost. When ECC recovery happens the block
is redirected to a spare, the data is written there and the
application has know idea anything happened. SMART data will tell you
how many times this has happened.




--
Al Dykes
-----------
adykes at p a n i x . c o m

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

"Wizard" <mskmywvcaqs@grubx.com> wrote in message news:4107E535.79B81BA6@grubx.com...
> My experience is that Blake is correct.

And another one from the school of hard knocks.

No, that is not what he said, it has nothing to do with the spare
pool being exhausted. Only how a "bad" sector manifests itself.

> Bad blocks, once seen, grow like weeds.

Yup, until you stop what's causing them.
Unrecoverable read error bad sectors are usually
caused by bad power supply or drives overheating.

>
> Eric Gisin wrote:
> >
> > Clueless gibberish. Read my and Folkert's reply to J Clarke.
> >
> > "Roger Blake" <rogblake10@iname10.com> wrote in message news:slrncgfgpk.las.rogblake10@unix2.netaxs.com...
> > >

["Clueless gibberish" snipped]

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

In article <2mqs11Fqeac5U2@uni-berlin.de>,
Folkert Rienstra <folkertdotrienstra@freeler.nl> wrote:
>
>"Wizard" <mskmywvcaqs@grubx.com> wrote in message news:4107E535.79B81BA6@grubx.com...
>> My experience is that Blake is correct.
>
>And another one from the school of hard knocks.
>
>No, that is not what he said, it has nothing to do with the spare
>pool being exhausted. Only how a "bad" sector manifests itself.
>
>> Bad blocks, once seen, grow like weeds.
>
>Yup, until you stop what's causing them.
>Unrecoverable read error bad sectors are usually
>caused by bad power supply or drives overheating.
>

IMHO once I see bad blocks the disk gets yanked and replaced on any PC
that's being used for business purposes. Life't too short to have
unexpected total failures.


>>
>> Eric Gisin wrote:
>> >
>> > Clueless gibberish. Read my and Folkert's reply to J Clarke.
>> >
>> > "Roger Blake" <rogblake10@iname10.com> wrote in message news:slrncgfgpk.las.rogblake10@unix2.netaxs.com...
>> > >
>
>["Clueless gibberish" snipped]


--
Al Dykes
-----------
adykes at p a n i x . c o m

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage,alt.computer (More info?)

Another clueless parrot troll.

"Roger Blake" <rogblake10@iname10.com> wrote in message news:slrncgfgpk.las.rogblake10@unix2.netaxs.com...
> On Mon, 26 Jul 2004 08:02:11 -0700, Eric Gisin <ericgisin@graffiti.net> wrote:
> >Nonsense. Your drive had bad sectors when it was shipped.
>
> Modern hard drives do bad block forwarding, invisible to the operating
> system and thus the end user. If you start actually seeing bad blocks
> it means that all the spares have been used and the drive is in the
> process of dying a grievous death.
>
> --
> Roger Blake
> (Subtract 10 for email.)

 

[Guest]

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

Next time, proofread your post before sending please.

"Taed Wynnell" <taedn@REMOVETHIS.vertical.com> wrote in message news:Y9QNc.1429$qo6.1874@news.uswest.net...
> "Roger Blake" <rogblake10@iname10.com> wrote in message news:slrncgfgpk.las.rogblake10@unix2.netaxs.com...
> > Modern hard drives do bad block forwarding, invisible to the operating
> > system and thus the end user. If you start actually seeing bad blocks
> > it means that all the spares have been used and the drive is in the
> > process of dying a grievous death.
>
> I don't think that's quite right based on my understanding.

> If you're WRITING to the block when the error is first detected
> by the drive, then the reallocation is invisible to the OS.

Only on 'sector not found', which isn't a possibility on recent drives without
sector IDs. Faulty writes will only be noticed on the next read to the sector.

> However, if a READ is the first time the error is detected, then
> an error is returned to the OS (and it will "detect" a bad block),

Only when it is an unrecoverable read error bad sector. Recoverable read
error bad sectors are the ones that are replaced directly (if needbe).

> but the disk then places that block number in a pending list and the reallocation

> isn't done

is done

> the next time it is written to.
> Thus, the OS could see an error before the spares have been exhausted.

Correct for unrecoverable read error bad sectors.

>
> This process is described in most detailed data sheets for the drives,
> and the 5 or so that I've read seem to follow this general process.

Correct, except that it is not like you explained here.

>
>