Can a hard drive be physically damaged due to power loss at startuptime?

[DJW]

I have a laptop whose main battier is dead. During booting up the
power cord became unplugged from the transformer. When I tried to
reboot I got a message about a second partition, which I did not have
on the hard drive. I assumed scandisk would run automatically and
things would straighten out. In my early try at getting the hard drive
to boot I also got a message that WINDOWS 98 HAS DECTECTED THAT DRIVE
C DOES NOT CONTAIN A VALID FAT or FAT32 PARTITION.
Here are some of the things I have tried and the messages I then got:
When I tried to install windows 98SE from the CD I got. SET UP CANNOT
INSTALL WINDOWS 98ON YOUR COMPUTER AN ERROR WAS DETECTED WHILE TRYING
TO READ OR WRITE TO YOUR HARD DISK

I tried at the a and then at the D and the C prompt FDISK I got one
set in where it asks to enable large disk support (my HD is 6.5 GB) I
tried yes first then no but both times it said ERROR READING FIXED
DISK Tried A:\>format c:/s still no luck.
Winbook the laptop manufacturer had some instructions on reinstalling
the OS. I tried with the CD in D:\win98> C: and get INVALID DRIVE
SPECIFICATIONS
Was running Ramdisk and getting no problem but then someone told me
that was scanning the ramdisk and so I booted from a floppy without a
reamdisk creator on it and tried scandisk and got a message worded
something like could not don it.

In the start up I see that my primary master IDE drive shows and in
the blue screen BIOS under Auto detect hard disk it shows and all
seems ok as far as the specs only the serial number does not show
anything. At startup the drive access light flashes and I can here it
spin and the actuator sound as it blinks.
At start up it says pri master hard drive S.M.A.R.T. Command failed. I
think this is the first roadblock problem why I can't boot. I changed
it from auto in the advanced setup to disabled still no luck.

I then got a diagnostic bootable CD from Hitachi the hard drive maker
and ran their DRIVE FITNESS TEST. It reported one or more corrupted
sectors found. When I said fix the sector it failed. I then tried to
erase the disk using their program and also got a failed.
My question from above is how can a hard drive that I never had a
problem with go bad because of the power going off but still appear to
the computer as being there with drive lamp working? Is there code
always on the hard drive that is not in its ROM that is screwed up and
I will never be able to right that. Could I have done in some RAM
(firmware setting) contained and set in its circuit board that I will
never be able to fix? My last information in this novel I have posted
here is that the Hitachi utility reported FAILURE CODE 0x75 DEFECTIVE
DEVICE COMPONENT FAILED TECHNICAL RESULT CODE 7573DCF0. Could this be
a dead CMOS battier? Or worse could this be the computer as in the IDE
controller. Could the power loss at start up changed some of the ROM
settings on the mother board?
I was and trying to install windows 98SE.

 

[Dave]

I have a laptop whose main battier is dead. During booting up the
power cord became unplugged from the transformer. When I tried to
reboot I got a message about a second partition, which I did not have
on the hard drive. I assumed scandisk would run automatically and
things would straighten out. In my early try at getting the hard drive
to boot I also got a message that WINDOWS 98 HAS DECTECTED THAT DRIVE
C DOES NOT CONTAIN A VALID FAT or FAT32 PARTITION.
Here are some of the things I have tried and the messages I then got:
When I tried to install windows 98SE from the CD I got. SET UP CANNOT
INSTALL WINDOWS 98ON YOUR COMPUTER AN ERROR WAS DETECTED WHILE TRYING
TO READ OR WRITE TO YOUR HARD DISK

I tried at the a and then at the D and the C prompt FDISK I got one
set in where it asks to enable large disk support (my HD is 6.5 GB) I
tried yes first then no but both times it said ERROR READING FIXED
DISK Tried A:\>format c:/s still no luck.
Winbook the laptop manufacturer had some instructions on reinstalling
the OS. I tried with the CD in D:\win98> C: and get INVALID DRIVE
SPECIFICATIONS
Was running Ramdisk and getting no problem but then someone told me
that was scanning the ramdisk and so I booted from a floppy without a
reamdisk creator on it and tried scandisk and got a message worded
something like could not don it.

In the start up I see that my primary master IDE drive shows and in
the blue screen BIOS under Auto detect hard disk it shows and all
seems ok as far as the specs only the serial number does not show
anything. At startup the drive access light flashes and I can here it
spin and the actuator sound as it blinks.
At start up it says pri master hard drive S.M.A.R.T. Command failed. I
think this is the first roadblock problem why I can't boot. I changed
it from auto in the advanced setup to disabled still no luck.

I then got a diagnostic bootable CD from Hitachi the hard drive maker
and ran their DRIVE FITNESS TEST. It reported one or more corrupted
sectors found. When I said fix the sector it failed. I then tried to
erase the disk using their program and also got a failed.
My question from above is how can a hard drive that I never had a
problem with go bad because of the power going off but still appear to
the computer as being there with drive lamp working? Is there code
always on the hard drive that is not in its ROM that is screwed up and
I will never be able to right that. Could I have done in some RAM
(firmware setting) contained and set in its circuit board that I will
never be able to fix? My last information in this novel I have posted
here is that the Hitachi utility reported FAILURE CODE 0x75 DEFECTIVE
DEVICE COMPONENT FAILED TECHNICAL RESULT CODE 7573DCF0. Could this be
a dead CMOS battier? Or worse could this be the computer as in the IDE
controller. Could the power loss at start up changed some of the ROM
settings on the mother board?
I was and trying to install windows 98SE.

Uhhhh, power loss is bad for electronics components, especially
motherboards. But as you got a message stating bad sectors, it is time to
replace your hard drive. Regardless of what else is wrong. So, you should
replace the hard drive and try again. If you still can't install an OS,
then you should suspect the mainboard at that point.

My suggestion would be to buy a fairly recent hard drive that can be used on
another system, if necessary. That is, you could always sell the hard drive
on craigslist or something if it turns out that you end up replacing the
whole laptop. But then, there's no law against using a 2.5" drive in a
desktop system. So you could buy a nice hard drive for the laptop and use
it for extra storage in a desktop if you end up not needing it for the
laptop.

Only thing I'm sure of is that your hard drive needs to be replaced. I'm
not sure why you can't install an OS on it. Could be bad hard drive, could
be bad mainboard. But even if you got this system working somehow, the
current hard drive IS failing, or is already dead. (one or the other) In
either case, it needs to be replaced. -Dave

 

[DJW]

Uhhhh, power loss is bad for electronics components, especially
motherboards. But as you got a message stating bad sectors, it is time to
replace your hard drive. Regardless of what else is wrong. So, you should
replace the hard drive and try again. If you still can't install an OS,
then you should suspect the mainboard at that point.

My suggestion would be to buy a fairly recent hard drive that can be used on
another system, if necessary. That is, you could always sell the hard drive
on craigslist or something if it turns out that you end up replacing the
whole laptop. But then, there's no law against using a 2.5" drive in a
desktop system. So you could buy a nice hard drive for the laptop and use
it for extra storage in a desktop if you end up not needing it for the
laptop.

Only thing I'm sure of is that your hard drive needs to be replaced. I'm
not sure why you can't install an OS on it. Could be bad hard drive, could
be bad mainboard. But even if you got this system working somehow, the
current hard drive IS failing, or is already dead. (one or the other) In
either case, it needs to be replaced. -Dave

I wrote Hitachi about the error message and got this reply with the
0x75 error there isn't much more that can happen with that hard drive.
If the hard drive was in the process of booting up and the power was
cut it could have caused issues with the hard drive with the read/
write head. It could have also cause a power corruption error."
Well that's a new one for me. So I guess they are saying give up
getting the drive to work! I guess that the head was not allowed to
park or something like that and now it's had it? Any way I was hoping
I would get some advice on how to fix it by a firmware update or
sending the drive back to them to have them work some magic. I will
replace the drive but my worry is that it was not the hard drive but
the computer in some way as in the IDE controller was damaged and a
new hard drive might have the same problem. Any thoughts from you if
that could be possible.

 

[Dave]

I wrote Hitachi about the error message and got this reply with the
0x75 error there isn't much more that can happen with that hard drive.
If the hard drive was in the process of booting up and the power was
cut it could have caused issues with the hard drive with the read/
write head. It could have also cause a power corruption error."
Well that's a new one for me. So I guess they are saying give up
getting the drive to work! I guess that the head was not allowed to
park or something like that and now it's had it? Any way I was hoping
I would get some advice on how to fix it by a firmware update or
sending the drive back to them to have them work some magic. I will
replace the drive but my worry is that it was not the hard drive but
the computer in some way as in the IDE controller was damaged and a
new hard drive might have the same problem. Any thoughts from you if
that could be possible.

If you are worried about the computer somehow damaging the new hard drive,
don't worry about that, it's not going to happen. At worst, you won't be
able to use the new hard drive if the IDE controller is bad.

Of course there is always the risk of another power failure, but nothing you
can do about that unless you want to run the whole system off a UPS.

It's possible that your hard drive failed AND your IDE controller failed.
If so, it might be time to think about a new laptop. Unfortunately, you
won't know until the hard drive is replaced. No easy way to narrow it down
further unless you could possibly find a 2.5" hard drive to borrow
momentarily? -Dave

 

[DJW]

If you are worried about the computer somehow damaging the new hard drive,
don't worry about that, it's not going to happen. At worst, you won't be
able to use the new hard drive if the IDE controller is bad.

Of course there is always the risk of another power failure, but nothing you
can do about that unless you want to run the whole system off a UPS.

It's possible that your hard drive failed AND your IDE controller failed.
If so, it might be time to think about a new laptop. Unfortunately, you
won't know until the hard drive is replaced. No easy way to narrow it down
further unless you could possibly find a 2.5" hard drive to borrow
momentarily? -Dave

This computer I used as a backup Internet machine and I played games
on it once in a while. I really have nothing I need to recover in the
way of files off of it.
Will I find all laptop hard drives the same in the back as far as the
main plug and the minimum size I need 2.5 by 1/8"? I think that is the
size. Hitachi seems to be saying the error code means the drive is
bad. The bad drive was only a 6.5 GB and I never had it full but I
can't find one that small on ebay all are 10 GB and way above that. I
really can only afford and want to put a small one in. This is just an
extra computer actually number four of five in the house. But can't
find one in my size and price range. Any good sources out there for
smaller used inexpensive ($15.00) with shipping drives. Just not the
selection like internal desktop IDE drives. I guess if the new (used)
drive will not work the computer will go in the trash and the HD, Ram,
transformer and CDROM will be posted on ebay for what ever I can get
for them maybe someone will have a use for them.

 

[Dave C.]

This computer I used as a backup Internet machine and I played games

on it once in a while. I really have nothing I need to recover in the
way of files off of it.
Will I find all laptop hard drives the same in the back as far as the
main plug and the minimum size I need 2.5 by 1/8"? I think that is the
size. Hitachi seems to be saying the error code means the drive is
bad. The bad drive was only a 6.5 GB and I never had it full but I
can't find one that small on ebay all are 10 GB and way above that. I
really can only afford and want to put a small one in. This is just an
extra computer actually number four of five in the house. But can't
find one in my size and price range. Any good sources out there for
smaller used inexpensive ($15.00) with shipping drives. Just not the
selection like internal desktop IDE drives. I guess if the new (used)
drive will not work the computer will go in the trash and the HD, Ram,
transformer and CDROM will be posted on ebay for what ever I can get
for them maybe someone will have a use for them.

You need a 2.5" IDE hard drive so that the drive will physically fit in your
notebook. $15 with shipping is going to be tough. I might look for a used
one on craigslist, maybe from another notebook that is being parted
ut. -Dave

 

[spodosaurus]

Power loss/brown outs cause more hard drive deaths than do 'surges'. I
run my critical systems off UPSs.

This computer I used as a backup Internet machine and I played games
on it once in a while. I really have nothing I need to recover in the
way of files off of it.
Will I find all laptop hard drives the same in the back as far as the
main plug and the minimum size I need 2.5 by 1/8"?

Size, yes, plug, no - laptop hard drives are either IDE or SATA, just
like desktop drives. You can use one or the other, they are not
interchangeable.

I think that is the
size. Hitachi seems to be saying the error code means the drive is
bad. The bad drive was only a 6.5 GB and I never had it full but I
can't find one that small on ebay all are 10 GB and way above that.

Your motherboard's BIOS may not be able to handle over 8GB for a hard
drive, and almost certainly not over 32GB. I think it might be time to
give the old laptop away to someone who can use it for parts and look
for something new(er).

I
really can only afford and want to put a small one in. This is just an
extra computer actually number four of five in the house.

Forget it then

But can't
find one in my size and price range. Any good sources out there for
smaller used inexpensive ($15.00) with shipping drives.

Any drives of that age that are second hand would be suspect as they may
have bad sectors, intermittent faults waiting for a crash, etc. But for
$15, I guess it's not like it's that costly of a gamble.

Just not the
selection like internal desktop IDE drives. I guess if the new (used)
drive will not work the computer will go in the trash and the HD, Ram,
transformer and CDROM will be posted on ebay for what ever I can get
for them maybe someone will have a use for them.

Just post the whole thing as you have it now, with a note that there's
no hard drive (assuming you test the IDE controller, otherwise you need
to make a note that the IDE controller hasn't been tested).

Ari


--
spammage trappage: remove the underscores to reply
Many people around the world are waiting for a marrow transplant. Please
volunteer to be a marrow donor and literally save someone's life:
http://www.abmdr.org.au/
http://www.marrow.org/

 

[Flasherly]

I have a laptop whose main battier is dead. During booting up the
power cord became unplugged from the transformer. When I tried to
reboot I got a message about a second partition, which I did not have
on the hard drive. I assumed scandisk would run automatically and
things would straighten out. In my early try at getting the hard drive
to boot I also got a message that WINDOWS 98 HAS DECTECTED THAT DRIVE
C DOES NOT CONTAIN A VALID FAT or FAT32 PARTITION.
Here are some of the things I have tried and the messages I then got:
When I tried to install windows 98SE from the CD I got. SET UP CANNOT
INSTALL WINDOWS 98ON YOUR COMPUTER AN ERROR WAS DETECTED WHILE TRYING
TO READ OR WRITE TO YOUR HARD DISK

I tried at the a and then at the D and the C prompt FDISK I got one
set in where it asks to enable large disk support (my HD is 6.5 GB) I
tried yes first then no but both times it said ERROR READING FIXED
DISK Tried A:\>format c:/s still no luck.
Winbook the laptop manufacturer had some instructions on reinstalling
the OS. I tried with the CD in D:\win98> C: and get INVALID DRIVE
SPECIFICATIONS
Was running Ramdisk and getting no problem but then someone told me
that was scanning the ramdisk and so I booted from a floppy without a
reamdisk creator on it and tried scandisk and got a message worded
something like could not don it.

In the start up I see that my primary master IDE drive shows and in
the blue screen BIOS under Auto detect hard disk it shows and all
seems ok as far as the specs only the serial number does not show
anything. At startup the drive access light flashes and I can here it
spin and the actuator sound as it blinks.
At start up it says pri master hard drive S.M.A.R.T. Command failed. I
think this is the first roadblock problem why I can't boot. I changed
it from auto in the advanced setup to disabled still no luck.

I then got a diagnostic bootable CD from Hitachi the hard drive maker
and ran their DRIVE FITNESS TEST. It reported one or more corrupted
sectors found. When I said fix the sector it failed. I then tried to
erase the disk using their program and also got a failed.
My question from above is how can a hard drive that I never had a
problem with go bad because of the power going off but still appear to
the computer as being there with drive lamp working? Is there code
always on the hard drive that is not in its ROM that is screwed up and
I will never be able to right that. Could I have done in some RAM
(firmware setting) contained and set in its circuit board that I will
never be able to fix? My last information in this novel I have posted
here is that the Hitachi utility reported FAILURE CODE 0x75 DEFECTIVE
DEVICE COMPONENT FAILED TECHNICAL RESULT CODE 7573DCF0. Could this be
a dead CMOS battier? Or worse could this be the computer as in the IDE
controller. Could the power loss at start up changed some of the ROM
settings on the mother board?
I was and trying to install windows 98SE.

I've an old IBM Thinkpad with IBM tech routines for low-level
formating the HD. Would take hours, but got back the drive. Real
picky about what sort of memory stratagem went into the upper 384 over
640 to access EMS, and would blow off the HD in a bad way. A low-
level is a last ditch attempt to recover a drive;- subsequent and
continued sector errors is not a good thing.

 

[DJW]

I've an old IBM Thinkpad with IBM tech routines for low-level
formating the HD. Would take hours, but got back the drive. Real
picky about what sort of memory stratagem went into the upper 384 over
640 to access EMS, and would blow off the HD in a bad way. A low-
level is a last ditch attempt to recover a drive;- subsequent and
continued sector errors is not a good thing.

What are you talking about above? Sounds like geek Greek to me? I just
got another letter back from Hitachi they say the error code I gave
them about the bad drive does not exactly tell them what is wrong but
they say definitely an internal part has failed.
OK I have learned something here, that a loss of power during booting
can cause physical damage to the hard drives. Does this apply to all
IDE hard drive as in an external in a USB box? And also a desktop's
internal drives. Is this something that either the master or slave can
have happen to it or was it something specific to a small profile type
laptop drive only?
I am an old time Mac user and mostly dealt with SCSI drives. Now I
can't ever say for sure that I ever had a power outage with a SCSI
drive during boot up. Does anyone out there know if damage can happen
to a SCSI during boot up due to loss of power? And does a Mac have the
same possible vulnerability to power loss during boot up now because
for a number of years they are using IDE drive also?
Should I post my last two questions to a Mac group or are there some
multi platform people here like me?

 

[Paul]

What are you talking about above? Sounds like geek Greek to me? I just
got another letter back from Hitachi they say the error code I gave
them about the bad drive does not exactly tell them what is wrong but
they say definitely an internal part has failed.
OK I have learned something here, that a loss of power during booting
can cause physical damage to the hard drives. Does this apply to all
IDE hard drive as in an external in a USB box? And also a desktop's
internal drives. Is this something that either the master or slave can
have happen to it or was it something specific to a small profile type
laptop drive only?
I am an old time Mac user and mostly dealt with SCSI drives. Now I
can't ever say for sure that I ever had a power outage with a SCSI
drive during boot up. Does anyone out there know if damage can happen
to a SCSI during boot up due to loss of power? And does a Mac have the
same possible vulnerability to power loss during boot up now because
for a number of years they are using IDE drive also?
Should I post my last two questions to a Mac group or are there some
multi platform people here like me?

http://www.hgst.com/tech/techlib.nsf/products/Travelstar_7K100
http://www.hgst.com/tech/techlib.ns...61AF1086256FEF00544C6A/$file/T7K100_sp1.3.pdf


"Travelstar 7K100 Hard Disk Drive Specification

11.4.2 Emergency unload

When the drive power is interrupted while the heads are still loaded, the
microcode cannot operate and the normal 5V power is unavailable to unload
the heads. In this case, normal unload is not possible, so the heads are
unloaded by routing the back EMF of the spinning motor to the voice coil.
The actuator velocity is greater than the normal case and the unload process
is inherently less controllable without a normal seek current profile.

Emergency unload is intended to be invoked in rare situations. Because
this operation is inherently uncontrolled, it is more mechanically stressful
than a normal unload. A single emergency unload operation is more stressful
than 100 normal unloads. Use of emergency unload reduces the start/stop life
of the drive at a rate at least 100 times faster than that of normal unload
and may damage the drive. <----------------------------------------- !!!!

11.4.3 Required power-off sequence

The following are examples of problems which can occur on most drives when
power is removed at an arbitrary time:

• Data is lost from the write buffer.
• If the drive is writing a sector, a partially written sector with an
incorrect ECC block results, the sector contents are destroyed, and reading
that sector results in a hard error.
• Heads may land in the data zone instead of the landing zone depending on
the design of the drive.

You may then turn off the drive by doing the following steps:
1. Issue Standby Immediate or sleep command
2. Wait until COMMAND COMPLETE STATUS is returned. (It may take up to 350 ms
in a typical case.)
3. Terminate power to drive

This power-down sequence should be followed for entry into any system
power-down state, system suspend state, or system hibernation state. In a
robustly designed system, emergency unload is limited to rare scenarios such as
battery removal during operation."

At least they've CYA in that description. There are probably some other
failure scenarios, such as a bad design, that writes important information
during "housekeeping" operations, and corruption of some of that information
is crucial to the drive starting properly the next time. Even a tech doc like
the above, may not reflect all the details of drive operation, or some of the
more common fault modes caused by bad firmware design decisions. Some drive
failures, for example, are caused by data structures that run out of room, and
the firmware deals with it, destructively. (I.e. A different firmware design,
would have meant fewer failures experienced by customers.) There are all sorts
of secrets about various drive designs out there, some of which you can
find and marvel at. Some dead drives are mechanically just fine, and it
is a defect map or some other data structure, which is preventing the
firmware from listening to host commands.

Paul

 

[DJW]

http://www.hgst.com/tech/techlib.ns.../techlib.nsf/techdocs/936114287A61AF1086256FE...

"Travelstar 7K100 Hard Disk Drive Specification

11.4.2 Emergency unload

When the drive power is interrupted while the heads are still loaded, the
microcode cannot operate and the normal 5V power is unavailable to unload
the heads. In this case, normal unload is not possible, so the heads are
unloaded by routing the back EMF of the spinning motor to the voice coil.
The actuator velocity is greater than the normal case and the unload process
is inherently less controllable without a normal seek current profile.

Emergency unload is intended to be invoked in rare situations. Because
this operation is inherently uncontrolled, it is more mechanically stressful
than a normal unload. A single emergency unload operation is more stressful
than 100 normal unloads. Use of emergency unload reduces the start/stop life
of the drive at a rate at least 100 times faster than that of normal unload
and may damage the drive. <----------------------------------------- !!!!

11.4.3 Required power-off sequence

The following are examples of problems which can occur on most drives when
power is removed at an arbitrary time:

* Data is lost from the write buffer.
* If the drive is writing a sector, a partially written sector with an
incorrect ECC block results, the sector contents are destroyed, and reading
that sector results in a hard error.
* Heads may land in the data zone instead of the landing zone depending on
the design of the drive.

You may then turn off the drive by doing the following steps:
1. Issue Standby Immediate or sleep command
2. Wait until COMMAND COMPLETE STATUS is returned. (It may take up to 350 ms
in a typical case.)
3. Terminate power to drive

This power-down sequence should be followed for entry into any system
power-down state, system suspend state, or system hibernation state. In a
robustly designed system, emergency unload is limited to rare scenarios such as
battery removal during operation."

At least they've CYA in that description. There are probably some other
failure scenarios, such as a bad design, that writes important information
during "housekeeping" operations, and corruption of some of that information
is crucial to the drive starting properly the next time. Even a tech doc like
the above, may not reflect all the details of drive operation, or some of the
more common fault modes caused by bad firmware design decisions. Some drive
failures, for example, are caused by data structures that run out of room, and
the firmware deals with it, destructively. (I.e. A different firmware design,
would have meant fewer failures experienced by customers.) There are all sorts
of secrets about various drive designs out there, some of which you can
find and marvel at. Some dead drives are mechanically just fine, and it
is a defect map or some other data structure, which is preventing the
firmware from listening to host commands.

Paul

Paul,
You are the first one to actually address my question's title as in
how a drive can or might be damaged during boot up. Do you have any
idea if it involves Mac with IDEs too or SCSI drives?
So the actuator my have been damaged by the force it was moved? Or if
it was scrambled code on the drive's platter(s) or firmware would a
flashing or update of the firm where possible help? Do my questions
make sense? Am I finally getting what the problem might be?

 

[Paul]

Paul,
You are the first one to actually address my question's title as in
how a drive can or might be damaged during boot up. Do you have any
idea if it involves Mac with IDEs too or SCSI drives?
So the actuator my have been damaged by the force it was moved? Or if
it was scrambled code on the drive's platter(s) or firmware would a
flashing or update of the firm where possible help? Do my questions
make sense? Am I finally getting what the problem might be?

As a general rule, end-user repair of drives is seldom successful.
There are suggestions like "put drive in a baggie in the freezer",
or individuals who'll tell you "yes, I opened the HDA and the drive
still worked afterwards". Some people advocate changing the
controller board, thinking all the problems will be solved
by doing that.

For example, a couple of people now, have methodically searched
Ebay, located an identical drive, swapped controller board from
good drive to bad drive, and got no response for their efforts.

If the data is valuable, contact a data recovery company. Prices
might range from $500 to a couple thousand, depending on the
amount of effort needed to get at the data. For some problems,
the recovery expert knows of the simple things that cause
drive failure. One drive, is known to use a defective motor
controller IC, and soldering a new one in place is all that
is needed to get the drive to spinup again.

In the worst case, the drive has to be opened, and the head
assembly replaced. Removing the platters, to me at least,
seems like a bad move, because the tracks would no longer
be concentric with respect to the hub. Whether they can
actually remove platters, and get the thing to work,
is unknown to me. When they replace a head assembly, they
may do that with the platters remaining secured to the hub.

AFAIK, the tracks are written on the platters, after the
platter is clamped to the hub. So the concentricity is
guaranteed, by the track writing machine, whatever that is.
But removing the platters, means the relationship between
concentric track and hub, has been disrupted.

The flying height of drive heads is such, that any dust that
enters the drive, will lead to eventual failure. Inside the
drive, there are a couple filter paks, that capture any
material scraped up via friction (like from the ramp). The
inside of the drive has a defined airflow, and the filters
are placed to try to capture loose debris. Opening the
HDA and introducing the extremely dirty room air, means the
drive will not last very long at all. Clean room techniques
are used for working inside a drive. For example, see the
guy in the bunny suit here.

http://services.seagate.com/facilities.aspx

When I mention "clean", I think back to the hard drive manufacturing
facility my company used to own. I was sent there on business
once. The drive assembly area, is Class 10 or 100, but the
floors of the cafeteria and hallways near the manufacturing
area, were dirty It seemed hygiene was only a consideration
once inside the manufacturing area. And that always made me
laugh, as it was such a contrast. You'd think people petrified
of dirt, would have washed the floors outside the manufacturing
area more often. Our silicon foundry, by comparison, was
spotless.

Paul