OT: bad sector remapping
D Yuniskis
I'm putting together a laptop for a friend. Clean install
of XP. Add required drivers, etc.
At this point, I would normally take a snapshot of the
disk (restoring from snapshot is *much* quicker than
reinstalling, etc.).
Doing so, Clonezilla claims a couple of bad sectors
(I'd have to doublecheck the log to see which tool
complained).
I believe this as the "disk check" built into the
BIOS gave a supper informative "Error #2" or somesuch.
Machine operates normally, otherwise.
So, is XP smart enough to avoid the bad sector?
Or, has it just not stumbled across it, yet?
I had thought modern PATA drives had finally adopted
the "grown defect table" support SCSI drives have
had. And, that the drive itself would take care
of the necessary housekeeping (i.e., to map a "good"
physical sector in to replace the bad one).
I've checked the Fujitsu site (seems they have sold
off their drive business to Toshiba?) but nothing like
a "low level format" utility there -- or any other
diagnostic/maintenance tool.
It's a 100G drive so I'd hate to discard it. But, I
think I have some 160's I could call on to replace it
if push comes to shove...
<frown> I hate this time of year! :-/
Thx,
--don
Przemek Klosowski
> Doing so, Clonezilla claims a couple of bad sectors (I'd have to
> doublecheck the log to see which tool complained).
> So, is XP smart enough to avoid the bad sector? Or, has it just not
> stumbled across it, yet?
No, it's in the disk firmware. If it can recover data using its array of
tricks (error correction, re-seeks and recalibration), it'll remap the
bad sectors, and return correct data, possibly after a significant delay.
If it can't recover the data, it reports disk reading errors, and XP
can't do anything about it.
>
> I had thought modern PATA drives had finally adopted the "grown defect
> table" support SCSI drives have had. And, that the drive itself would
> take care of the necessary housekeeping (i.e., to map a "good" physical
> sector in to replace the bad one).
Since late 1990s practically all disks have the firmware diagnostics
called SMART. They can be read from ATA, SATA, SAS and even USB
interfaces. In Linux SMART data can be read via the skdump and smartctl
commands, and a very nice disk utility called 'palimpsest' that can read
SMART data, run SMART tests, and even characterize disk speed dependence
on sector location. Some BIOSes display SMART status, but w/o much detail.
There are manufacturer utilities to show SMART; they should be vendor-
independent, actually, because SMART is almost standard.
While the firmware can swap out recoverable bad sectors, there was a
Google paper showing that any bad sectors are a significant predictor of
a future complete disk failure. Watch for Reallocated Sector Count
(recovered errors) and especially Current Pending Sector (unrecoverable
errors).
> <frown> I hate this time of year! :-/
>
Bah, humbug, as well :)
D Yuniskis
On 12/20/2010 9:04 PM, Przemek Klosowski wrote:
> On Mon, 20 Dec 2010 18:47:49 -0700, D Yuniskis wrote:
>
>> Doing so, Clonezilla claims a couple of bad sectors (I'd have to
>> doublecheck the log to see which tool complained).
> ...
>> So, is XP smart enough to avoid the bad sector? Or, has it just not
>> stumbled across it, yet?
>
> No, it's in the disk firmware. If it can recover data using its array of
> tricks (error correction, re-seeks and recalibration), it'll remap the
> bad sectors, and return correct data, possibly after a significant delay.
> If it can't recover the data, it reports disk reading errors, and XP
> can't do anything about it.
Yes, that's what I expected. So, the fact that XP didn't complain
during the format, install and a subsequent "defragment" suggests it
simply didn't *touch* that sector (?).
By contrast, Clonezilla *did* (suggesting that Windows had put
something *in* it) access it and complain.
<frown>
I stumbled across "MHDD" which *seems* like it should be able
to do what I need. Of course, at an hour per pass, it will
be a while before I can go through the entire install with
Clonezilla chaser.
I'll post back when I have more conclusive results.
>> I had thought modern PATA drives had finally adopted the "grown defect
>> table" support SCSI drives have had. And, that the drive itself would
>> take care of the necessary housekeeping (i.e., to map a "good" physical
>> sector in to replace the bad one).
>
> Since late 1990s practically all disks have the firmware diagnostics
> called SMART. They can be read from ATA, SATA, SAS and even USB
> interfaces. In Linux SMART data can be read via the skdump and smartctl
> commands, and a very nice disk utility called 'palimpsest' that can read
> SMART data, run SMART tests, and even characterize disk speed dependence
> on sector location. Some BIOSes display SMART status, but w/o much detail.
> There are manufacturer utilities to show SMART; they should be vendor-
> independent, actually, because SMART is almost standard.
>
> While the firmware can swap out recoverable bad sectors, there was a
> Google paper showing that any bad sectors are a significant predictor of
> a future complete disk failure. Watch for Reallocated Sector Count
> (recovered errors) and especially Current Pending Sector (unrecoverable
> errors).
I thought the paper mentioned how *bad* SMART was at predicting
failures (?)
>> <frown> I hate this time of year! :-/
>
> Bah, humbug, as well :)
<grin> End of year replacing equipment (and finding new homes
for the old stuff) always ends up eating up far more time than
I expect! :-/
David Brown
> Hi Przemek,
>
> On 12/20/2010 9:04 PM, Przemek Klosowski wrote:
>> On Mon, 20 Dec 2010 18:47:49 -0700, D Yuniskis wrote:
>>
>>> Doing so, Clonezilla claims a couple of bad sectors (I'd have to
>>> doublecheck the log to see which tool complained).
>> ...
>>> So, is XP smart enough to avoid the bad sector? Or, has it just not
>>> stumbled across it, yet?
>>
>> No, it's in the disk firmware. If it can recover data using its array of
>> tricks (error correction, re-seeks and recalibration), it'll remap the
>> bad sectors, and return correct data, possibly after a significant delay.
>> If it can't recover the data, it reports disk reading errors, and XP
>> can't do anything about it.
>
> Yes, that's what I expected. So, the fact that XP didn't complain
> during the format, install and a subsequent "defragment" suggests it
> simply didn't *touch* that sector (?).
>
> By contrast, Clonezilla *did* (suggesting that Windows had put
> something *in* it) access it and complain.
>
The disk will only report bad sectors when /reading/. If it notices a
failure during a write (this is very rare), it will silently re-locate
that sector to one of its spare sectors (unless, of course, the drive is
so bad that it runs out of spares). When reading a sector, the disk can
correct a number of errors. If the errors reach a certain threshold,
then again the disk will silently re-locate the sector and return the
corrected data. But if there were uncorrectable errors, the disk
returns an error message.
Think about what happens during an NTFS format. Assuming it is a
"quick" format, very little is actually written to the disk - just the
superblocks and a skeleton MFT. And /nothing/ is read - thus bad
sectors will not be found. During installation of XP, very little is
read - most access is writing to the disk, so again the chances of
spotting a failure are small. In use, XP will obviously read from the
disk - but only the sectors it needs, which is a small proportion of the
total written data. But when Clonezilla is copying a disk, it will read
/everything/ - if there are errors, these will show up.
It is also possible that Clonezilla does a more low-level read and gets
information about poor or failing sectors rather than just unrecoverably
failed sectors. I don't know if that's the case or not - you would have
to check in the Clonezilla documentation.
Robert Roland
>So, is XP smart enough to avoid the bad sector?
Yes, but not "on the fly", as the drive does internally. If you run a
chkdsk /F/R, Windows will test all sectors and try to relocate the
data in the bad sectors to a good sector. It is unlikely the recovery
will succeed, but at least it will let you know which file is lost.
>Or, has it just not stumbled across it, yet?
Quite possible. There are lots of files that are almost never used,
and even quite a few that are never used in normal operation.
>I had thought modern PATA drives had finally adopted
>the "grown defect table" support SCSI drives have
>had.
They do. The problem is that this defect table is of limited size, and
when it is full, the drive has to start marking additional bad sectors
the old fashioned way.
This means that once you see the first bad sector, there are actually
hundreds, maybe thousands of bad sectors already. This is caused by a
fault in the drive, and this fault will cause more bad sector to
appear with time.
>I've checked the Fujitsu site (seems they have sold
>off their drive business to Toshiba?) but nothing like
>a "low level format" utility there
Modern drives use a voice coil to position the heads. Such drives
cannot be low level formatted, because they need the servo information
on the platters to position the heads. If you erase the platters with
a strong magnetic field, the drive will start to hopelessly clank the
heads against the end stop, desperately trying to find the servo
information.
> -- or any other
>diagnostic/maintenance tool.
That's poor customer service. But if the BIOS says the drive is bad,
and a different drive tests OK, then it *is* bad.
>It's a 100G drive so I'd hate to discard it.
The drive is broken. If you don't want to discard it, use it as a
paperweight.
If you continue to use the drive, you will experience neverending,
random problems, and you may hate Windows for being so unstable. Note
that a bad sector propping up in the page file will cause a bluescreen
crash with a message suggesting a memory error. Once sector zero dies,
you will no longer be able to use the drive on a Wintel BIOS based
machine.
Do yourself a favor: Replace the drive.
--
RoRo
d_s_klein
> On Mon, 20 Dec 2010 18:47:49 -0700, D Yuniskis
>
> >So, is XP smart enough to avoid the bad sector?
>
> Yes, but not "on the fly", as the drive does internally. If you run a
> chkdsk /F/R, Windows will test all sectors and try to relocate the
> data in the bad sectors to a good sector. It is unlikely the recovery
> will succeed, but at least it will let you know which file is lost.
>
Not *exactly* correct. If chkdsk encounters an unused bad sector it
will it to the bad sector list. A status line from chkdsk reports the
number of bad sectors if it is non-zero. That sector will be avoided
(not remapped) until the next re-format.
>
> Do yourself a favor: Replace the drive.
> --
I agree 1000%. The cost of the drive (1T < $100) is dwarfed by the
cost of the data.
> RoRo
RK
Dave Platt
Robert Roland <fa...@ddress.no> wrote:
>Do yourself a favor: Replace the drive.
Excellent advice. The cost of a simple replacement is relatively
small (around $50), the cost to you of lost productivity and/or data
could be far higher if your current drive fails completely, and your
current drive probably *will* fail completely before long no matter
what you do.
--
Dave Platt <dpl...@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
Dave Platt
Przemek Klosowski <prz...@tux.dot.org> wrote:
>While the firmware can swap out recoverable bad sectors, there was a
>Google paper showing that any bad sectors are a significant predictor of
>a future complete disk failure. Watch for Reallocated Sector Count
>(recovered errors) and especially Current Pending Sector (unrecoverable
>errors).
That matches what I've seen, over the past ten years of doing
hard-drive support at TiVo for DVR applications.
It's common for drives to have a small number of "grown" defects over
its lifetime (i.e. bad sectors which were not detected during factory
formatting, but have "gone bad" during use). However, once you see
more than a very few of these, or get several of them occurring in a
fairly short period of time, it's a pretty good sign that the drive is
on a rapidly-descending path to total failure, and it's time to back
up it (if you haven't already, shame on you) and replace it.
I discussed the issue with engineers from a couple of hard-drive
manufacturers, and believe that there's a good reason why this is the
case. In modern hard drives, the read/write head is flying over the
media surface at a *very* low height -- the width of a human hair is
huge by comparison, and even a particle of cigarette smoke looks like
a boulder. If there's any contaminating particle at all on the disk
surface, it'll get between the head and the surface and cause the head
to "bounce" or scrape. Even if it doesn't force the head away from
the platter, it causes enough friction to heat up the tiny read/write
head and change its electrical characteristics, resulting in a bad
read (the engineers used the term "thermal asperity" to refer to this
sort of event).
A major reason for the development of bad sectors, is physical damage:
"head slap", in which the head actually hits the platter and knocks
some particles loose. Thie can happen if the drive or computer is
banged or moved sharply while the drive is spinning, or even when it's
powered off. If these particles remain on the disk surface (or fly
away and then land again, elsewhere) they're likely to be hit by the
head during a subsequent revolution... which can cause more scraping
or even slapping of the head, more damage to the surface, and the
creation of more loose particles. Although the drives have a fiber
filter in the air-flow path which is intended to catch these
particles, it's never 100% effective... and so the amount of
contamination builds up as time goes by, and the problem snowballs and
the drive goes downhill towards failure.
After playing around with a number of error-management ideas at TiVo,
I came to the conclusion that it wasn't worth bothering with. A drive
which shows a significant number of reallocated (or pending-
reallocation) sectors, probably doesn't have very long to live...
its performance will degrade (due to the need to retry reads on
sectors that are going bad) and it will lose more and more data
(unrecoverable errors). The best filesystem- and application-level
error management techniques I could dream up, wouldn't have extended
the life of a failing drive enough to be worth the effort and
complexity.
D Yuniskis
On 12/21/2010 7:28 AM, Robert Roland wrote:
> On Mon, 20 Dec 2010 18:47:49 -0700, D Yuniskis
> <not.goi...@seen.com> wrote:
>
>> So, is XP smart enough to avoid the bad sector?
>
> Yes, but not "on the fly", as the drive does internally. If you run a
> chkdsk /F/R, Windows will test all sectors and try to relocate the
> data in the bad sectors to a good sector. It is unlikely the recovery
> will succeed, but at least it will let you know which file is lost.
My point is that windows' (possessive) handling of the error
must be done at a higher level (abstraction) than the remapping
that the drive is *supposed* to be doing. I.e., it modifies
some structure in the filesystem that *it* (windows) maintains;
and does NOT force the drive to remap the sector.
[this makes sense if the "application" sits in userland and
isn't tightly integrated into the OS -- otherwise, the OS
would have to export the "remap bad HARDWARE sector" facility
in its API]
E.g., I re-did the install. Chkdsk. Defrag. etc. and partclone
(part of Clonezilla) *still* complained about a bad sector.
So, what I did last night (while waiting for the moon to creep
into shadow) was to run this utility. repeatedly. (takes a bit
over an hour to scan the drive). Each time, the same sector was
flagged as "bad". Sector number corresponded with the one
reported by partclone.
Then, had that utility "remap" the sector. And, another scan.
Sector no longer reported as bad. Though in its place, the
"new" sector shows an increased access time (utility graphically
depicts access times of each sector -- so, you can "see" each
time the head moves to a new cylinder as the first access in
that cylinder will be higher than all subsequent ones) no doubt
a result of the drive having to "fetch" the remapped cyclinder.
Ran the BIOS "test hard disk" utility. Passed without complaint.
Reinstalled windows. chkdsk. defragment. Still no complaints.
Ran clonezilla. Successfully completed in ~4 minutes (i.e., I
can now do a "restore" in about the same amount of time -- not
the hours that a new windows install would require!)
>> Or, has it just not stumbled across it, yet?
>
> Quite possible. There are lots of files that are almost never used,
> and even quite a few that are never used in normal operation.
But, in theory, chkdsk would have examined EVERY sector on
the drive, even those not currently in use by "files" (or
"superblock")
>> I had thought modern PATA drives had finally adopted
>> the "grown defect table" support SCSI drives have
>> had.
>
> They do. The problem is that this defect table is of limited size, and
> when it is full, the drive has to start marking additional bad sectors
> the old fashioned way.
>
> This means that once you see the first bad sector, there are actually
> hundreds, maybe thousands of bad sectors already. This is caused by a
> fault in the drive, and this fault will cause more bad sector to
> appear with time.
>
>> I've checked the Fujitsu site (seems they have sold
>> off their drive business to Toshiba?) but nothing like
>> a "low level format" utility there
>
> Modern drives use a voice coil to position the heads. Such drives
> cannot be low level formatted, because they need the servo information
> on the platters to position the heads. If you erase the platters with
> a strong magnetic field, the drive will start to hopelessly clank the
> heads against the end stop, desperately trying to find the servo
> information.
Yes, we bulk erase (and/or drill a 3/8" dia hole through the
drive) drives headed out for "scrap". Amusing to see folks
try to resurrect a drive that has been bulk erased (but not
yet drilled).
>> -- or any other
>> diagnostic/maintenance tool.
>
> That's poor customer service. But if the BIOS says the drive is bad,
> and a different drive tests OK, then it *is* bad.
BIOS only complained when explicitly asked to "test hard drive".
Obviously did a surface scan and complained when it encountered this
sector (this is speculation on my part; error message was totally
useless -- the equivalent of "check engine").
>> It's a 100G drive so I'd hate to discard it.
>
> The drive is broken. If you don't want to discard it, use it as a
> paperweight.
>
> If you continue to use the drive, you will experience neverending,
> random problems, and you may hate Windows for being so unstable. Note
> that a bad sector propping up in the page file will cause a bluescreen
> crash with a message suggesting a memory error. Once sector zero dies,
> you will no longer be able to use the drive on a Wintel BIOS based
> machine.
>
> Do yourself a favor: Replace the drive.
As I said, I have several other drives. But, my experience has
been that getting *at* the drive often results in damage to the
case (the 'snaps" on these cheap plastic clamshells invariably
break). So, if it boils down to open the case to replace the drive,
I'll turn the disk off in the BIOS and use it as a diskless
workstation (which pretty much eliminates it's usefulness as
a laptop -- just turns it into a "portable, *wired* computer")
Or, "recycle" it.
For now, everything *looks* like it is working. So, I'll
install the rest of the applications and periodically
"scan" the disk by doing periodic partclones. (I can ALWAYS
discard it at a later date! :> )
Thanks!
D Yuniskis
> On Dec 21, 6:28 am, Robert Roland<f...@ddress.no> wrote:
>> On Mon, 20 Dec 2010 18:47:49 -0700, D Yuniskis
>>
>> <not.going.to...@seen.com> wrote:
>>> So, is XP smart enough to avoid the bad sector?
>>
>> Yes, but not "on the fly", as the drive does internally. If you run a
>> chkdsk /F/R, Windows will test all sectors and try to relocate the
>> data in the bad sectors to a good sector. It is unlikely the recovery
>> will succeed, but at least it will let you know which file is lost.
>
> Not *exactly* correct. If chkdsk encounters an unused bad sector it
> will it to the bad sector list. A status line from chkdsk reports the
But, is this list at filesystem level or *within* the drive (e.g.,
"grown defect list")?
> number of bad sectors if it is non-zero. That sector will be avoided
> (not remapped) until the next re-format.
This suggests the list is in an OS-maintained structure and NOT in
the drive itself. It also suggests that formatting purges the
list (?). I.e., format by itself will just re-introduce the
flakey sector back into the pool of available sectors (until the
next chkdsk)
>> Do yourself a favor: Replace the drive.
>
> I agree 1000%. The cost of the drive (1T< $100) is dwarfed by the
> cost of the data.
Machine will just be used for email and to view camera photos
off SC cards while traveling. As I said elsewhere, opening the
case to replace the drive stands a good chance of damaging the
case (I repair rescued laptops for a local non-profit so I am
well aware of how easily they can be trashed -- having trashed
far too many, myself! :> ). Some laptops are a bit friendlier
for the "common" repairs (swap drives, swap PCI modules, swap
memory -- some are even cooperative in replacing the CD/DVD!).
This one isn't. :-/
The consolation is that if it starts acting up "while traveling",
it can just be dumped into the nearest trash can :>
d_s_klein
> On 12/21/2010 9:04 AM, d_s_klein wrote:
>
> > On Dec 21, 6:28 am, Robert Roland<f...@ddress.no> wrote:
> >> On Mon, 20 Dec 2010 18:47:49 -0700, D Yuniskis
>
> >> <not.going.to...@seen.com> wrote:
> >>> So, is XP smart enough to avoid the bad sector?
>
> >> Yes, but not "on the fly", as the drive does internally. If you run a
> >> chkdsk /F/R, Windows will test all sectors and try to relocate the
> >> data in the bad sectors to a good sector. It is unlikely the recovery
> >> will succeed, but at least it will let you know which file is lost.
>
> > Not *exactly* correct. If chkdsk encounters an unused bad sector it
> > will it to the bad sector list. A status line from chkdsk reports the
>
> But, is this list at filesystem level or *within* the drive (e.g.,
> "grown defect list")?
>
> > number of bad sectors if it is non-zero. That sector will be avoided
> > (not remapped) until the next re-format.
>
> This suggests the list is in an OS-maintained structure and NOT in
> the drive itself. It also suggests that formatting purges the
> list (?). I.e., format by itself will just re-introduce the
> flakey sector back into the pool of available sectors (until the
> next chkdsk)
>
There is a bad sector list that is maintained by the OS on the hard
drive as part of the file system. Every file system I have ever
worked with has such a feature, and I date back to the RT-11 days.
Typical method is the mark the sector (cluster) as 'unavailable' -
before- it is attached to a file, and it gets skipped when the OS
searches for the next available sector (cluster).
When you build a new file system, this list typically starts at
"empty". One exception is the Windows floppy format - it scans the
disk and builds a new list every time unless you specifically tell it
not to. There are probably options to the other format routines to
force it to build a new list. (I use chkdsk with surface scan
immediately after formatting.) In the 'pre-IDE' days, one got a chart
with the drive, and format was told about the bad sectors "by hand".
RK
d_s_klein
>
> Machine will just be used for email and to view camera photos
> off SC cards while traveling. As I said elsewhere, opening the
> case to replace the drive stands a good chance of damaging the
> case (I repair rescued laptops for a local non-profit so I am
> well aware of how easily they can be trashed -- having trashed
> far too many, myself! :> ). Some laptops are a bit friendlier
> for the "common" repairs (swap drives, swap PCI modules, swap
> memory -- some are even cooperative in replacing the CD/DVD!).
>
> This one isn't. :-/
>
> The consolation is that if it starts acting up "while traveling",
> it can just be dumped into the nearest trash can :>
Configure it to boot off of a flash drive. Or boot off of a CD, and
use a flash drive for storage. - That way there is no data to recover
after it has breathed its last.
Or realize that you can get a bucket-class laptop for less than you've
'spent' so far on this one. :)
RK
Didi
> In article <iep90h$a0...@news.eternal-september.org>,
Thanks for the insight - the physical explanation why this happens
was something I could only have guesses about.
I am mostly using 2.5" drives and DPS (our OS here)
has all the defect detection etc. stuff, done in the early 90-s
(mostly on a SCSI 200 MB 2.5" drive, which was the largest then...
its R/W head must have been still of the inductive type, a little
later drives got much better and larger).
However all that stuff is practically unused since :-).
Can you say something on the life expectation of drives
which are on most if not all of the time? The SMART data
do have a spin up counter, perhaps this is the main killer,
but I wonder how long the bearing will last with little spin up/
down involved, the number of disks I have had in my hands is
dwarfed by the one your DVR experience suggests.
Dimiter
------------------------------------------------------
Dimiter Popoff Transgalactic Instruments
http://www.tgi-sci.com
------------------------------------------------------
http://www.flickr.com/photos/didi_tgi/sets/72157600228621276/
D Yuniskis
On 12/21/2010 7:18 PM, Didi wrote:
> Can you say something on the life expectation of drives
> which are on most if not all of the time? The SMART data
> do have a spin up counter, perhaps this is the main killer,
> but I wonder how long the bearing will last with little spin up/
> down involved, the number of disks I have had in my hands is
> dwarfed by the one your DVR experience suggests.
http://labs.google.com/papers/disk_failures.pdf
has some interesting insights
D Yuniskis
> When you build a new file system, this list typically starts at
This makes sense. I'd never considered the issue before.
> "empty". One exception is the Windows floppy format - it scans the
> disk and builds a new list every time unless you specifically tell it
> not to. There are probably options to the other format routines to
> force it to build a new list. (I use chkdsk with surface scan
> immediately after formatting.) In the 'pre-IDE' days, one got a chart
> with the drive, and format was told about the bad sectors "by hand".
Yes, I can remember old MFM drives with such lists. I only ever had
one DEC disk drive -- small (capacity, not size), 128 fixed heads.
I seem to recall it was essentially byte (word) addressable (?)
D Yuniskis
> On Dec 21, 10:39 am, D Yuniskis<not.going.to...@seen.com> wrote:
>
>>
>> Machine will just be used for email and to view camera photos
>> off SC cards while traveling. As I said elsewhere, opening the
>> case to replace the drive stands a good chance of damaging the
>> case (I repair rescued laptops for a local non-profit so I am
>> well aware of how easily they can be trashed -- having trashed
>> far too many, myself! :> ). Some laptops are a bit friendlier
>> for the "common" repairs (swap drives, swap PCI modules, swap
>> memory -- some are even cooperative in replacing the CD/DVD!).
>>
>> This one isn't. :-/
>>
>> The consolation is that if it starts acting up "while traveling",
>> it can just be dumped into the nearest trash can :>
>
> Configure it to boot off of a flash drive. Or boot off of a CD, and
> use a flash drive for storage. - That way there is no data to recover
> after it has breathed its last.
There *never* will be anything to "recover" on it. I don't use
laptops for anything other than "small GUI's". A friend will
be using this one to access email, browse the web and view
pictures from digital camera. I.e., all things that exist *outside*
the PC's disk.
> Or realize that you can get a bucket-class laptop for less than you've
> 'spent' so far on this one. :)
I volunteer at a recycling facility. This attitude is far too
common. "Recycled" machines (at most such places) I *scrapped*
for precious metals, etc. A huge waste of resources for something
that is typically still "serviceable" (it is not uncommon for
an 18-wheeler to pull up FULL of PC's to be recycled -- just because
some business decided that it's been 18 months since they last
purchased machines... :-/ ). Unfortunately, it takes a lot of
labor to reintroduce a machine into normal use once it has gone
this route. But, schools, charities, etc. sure appreciate NOT
having to pay for them!
I would prefer not to be a part of that problem.
do_not_...@my-deja.com
Robert Roland wrote:
> Modern drives use a voice coil to position the heads. Such drives
> cannot be low level formatted, because they need the servo information
> on the platters to position the heads.
Modern drives can't be low level formatted by the user, but not
because of the servo, which is written between the sectors or more
deeply than the other information. One early drive with an embedded
servo was the Toshiba MK-72x, an ST506/412 interface drive with 10
heads and 5 platters, and it could definitely be low level formatted.
Meat Plow
First HD I owned was a Kalok 330 RLL. I think it was around 30 megabytes.
The DEBUG command was used to low level format these and MFM drives.
Usually on an AT/XT PC it was > debug.com then G=C800:5.
Do you go back that far?
--
Live Fast, Die Young and Leave a Pretty Corpse
Jim Stewart
> First HD I owned was a Kalok 330 RLL. I think it was around 30 megabytes.
> The DEBUG command was used to low level format these and MFM drives.
> Usually on an AT/XT PC it was> debug.com then G=C800:5.
>
> Do you go back that far?
I've rewritten timing tracks on DEC DF32
and RF08 head-per-track drives when you
were in grade school.
Meat Plow
So is this "MY COCK IS BIGGER THAN YOURS" contest for you or do you
really think I give a fuck what you did or when you did it.
BTW I was is high school back when you were fiddling wither your DIC.
David Nebenzahl
Ah, Meat Head shows his good manners again ...
--
Comment on quaint Usenet customs, from Usenet:
To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.
Meat Plow
> On 12/22/2010 11:01 AM Meat Plow spake thus:
>
>> On Wed, 22 Dec 2010 10:46:28 -0800, Jim Stewart wrote:
>>
>>> Meat Plow wrote:
>>>
>>>> First HD I owned was a Kalok 330 RLL. I think it was around 30
>>>> megabytes. The DEBUG command was used to low level format these and
>>>> MFM drives. Usually on an AT/XT PC it was> debug.com then G=C800:5.
>>>>
>>>> Do you go back that far?
>>>
>>> I've rewritten timing tracks on DEC DF32 and RF08 head-per-track
>>> drives when you were in grade school.
>>
>> So is this "MY COCK IS BIGGER THAN YOURS" contest for you or do you
>> really think I give a fuck what you did or when you did it.
>>
>> BTW I was is high school back when you were fiddling wither your DIC.
>
> Ah, Meat Head shows his good manners again ...
The Revenge Dweeb chimes in right on cue. I never claimed to have good
manners you simpering fuckwit. Don't like what I post, don't read it.
Franc Zabkar
<not.goi...@seen.com> put finger to keyboard and composed:
>On 12/21/2010 9:04 AM, d_s_klein wrote:
>> On Dec 21, 6:28 am, Robert Roland<f...@ddress.no> wrote:
>>> On Mon, 20 Dec 2010 18:47:49 -0700, D Yuniskis
>>>
>>> <not.going.to...@seen.com> wrote:
>>>> So, is XP smart enough to avoid the bad sector?
>>>
>>> Yes, but not "on the fly", as the drive does internally. If you run a
>>> chkdsk /F/R, Windows will test all sectors and try to relocate the
>>> data in the bad sectors to a good sector. It is unlikely the recovery
>>> will succeed, but at least it will let you know which file is lost.
>>
>> Not *exactly* correct. If chkdsk encounters an unused bad sector it
>> will it to the bad sector list. A status line from chkdsk reports the
>
>But, is this list at filesystem level or *within* the drive (e.g.,
>"grown defect list")?
>
>> number of bad sectors if it is non-zero. That sector will be avoided
>> (not remapped) until the next re-format.
>
>This suggests the list is in an OS-maintained structure and NOT in
>the drive itself. It also suggests that formatting purges the
>list (?). I.e., format by itself will just re-introduce the
>flakey sector back into the pool of available sectors (until the
>next chkdsk)
The drive will wait for a Write command from the host (ie the OS)
before it processes a "pending" sector. When a write command is
issued, the drive retests the pending sector and returns it to service
if good, or reallocates the LBA to a spare sector if bad.
If CHKDSK finds a bad sector, then it takes it out of service and adds
it to the $BADCLUS metafile in the case of NTFS, or marks it as bad in
the File Allocation Table in the case of FAT16 or FAT32. Thereafter
the sector is never accessed again until the next time the drive is
formatted. In fact my own Seagate drive had 1 pending sector for its
entire life because Windows 98's Scandisk had marked it as bad.
In short, the list of bad clusters maintained by the OS, and the lists
of grown and factory defects (G-list and P-list) maintained by the
drive, are essentially unrelated. In fact, once a sector has made it
into into the G-list, it becomes invisible to the OS. All that the OS
sees is an LBA (Logical Block Address), not a physical sector.
Remapping or reallocation is the process by which the drive
transparently takes a sector from a pool of spares and assigns it to a
particular unreadable LBA. The host is never aware that this has
happened.
- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
Franc Zabkar
>I'm putting together a laptop for a friend. Clean install
>of XP. Add required drivers, etc.
>
>At this point, I would normally take a snapshot of the
>disk (restoring from snapshot is *much* quicker than
>reinstalling, etc.).
>
>Doing so, Clonezilla claims a couple of bad sectors
>(I'd have to doublecheck the log to see which tool
>complained).
Use a comprehensive SMART diagnostic tool. Look for reallocated,
pending, or uncorrectable sectors.
HD Sentinel (DOS / Windows / Linux):
http://www.hdsentinel.com/
HDDScan for Windows:
http://hddscan.com/
See this article for SMART info:
http://en.wikipedia.org/wiki/S.M.A.R.T.
MHDD can also display the SMART data.
A "low level format" on modern drives merely writes zeros to each
sector. It doesn't actually perform a real LLF. After zeroing the
drive, any "pending" sectors will be transparently retested and
reallocated with spares, if necessary.