🚀 go-pugleaf

"Rod Speed" <rod_speed@yahoo.com> wrote in message news:SFQx5.21094$cr3.540937@ozemail.com.au...
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| Ian Staples <ianst@refer.to.sig.au.invalid> wrote in
| message news:8q78tu$3m1$2@bunyip.cc.uq.edu.au...
| > phaywood@alphalink.com.au.REMOVE.THIS.BIT wrote:
| >> Steen Nielsen wrote
|
| >>> Hi I need a dos program to repaer bad sectores on my harddrive
| >>> can any one please tell me which program i should use.
|
| >> You can't fix bad sectors. They're a fact of life.
| >> There's really nothing you can do. Those sectors
| >> have gone to the great bit bucket in the sky.
|
| > Is everything so clearly black or white,
| > or can we have a bit of grey here too?
|
| If you insist, even a cane toad can have some grey.
|
| > Up until 72 hours ago I may have unconditionally agreed with
| > the "great bit bucket" concept, but I'm now wondering about it...
|
| Its just plain wrong stated as absolutely as that.
|
| It really depends on what produced what appears to be bad sectors.
| It is possible for some software to decide that a particular sector is
| bad at the OS level and just mark it as bad at the OS level, in the
| FAT. That can happen not because there is a problem at the level
| of the media layer on the platter but just due to errors higher in the
| chain so the software sees what appears to be a bad sector but
| which is fine at the level of the sector on the media.
|
| Those can obviously be fixed just by a format at the OS level.
|
| Even when a sector has gone bad on the physical platter, most
| modern drives do have what is often called a low level formatter
| but which in fact is just a ute which scans for and adds new bad
| sectors to the bad sector list

I think that is wrongly worded, see my other contrib.
On the other hand that is what we would like to have so we could get
rid of the unrecoverable read errors that the automatic reallocation process is unable to replace.

| and makes the drive appear to be error free.
| Clearly in that case the bad sector hasnt actually been
| repaired, only mapped away,

Technically and logically it is. Technically that spot is not a sector anymore, just unused space.

| but thats the least common reason
| for bad sectors because the original bad sector scan done at
| manufacturing time is done at reduced signal levels to detect areas
| where the media isnt good enough and that doesnt change over time.

I'd say it does: wear and tear.

|
| You can however sometimes get at bad sector due
| to a power glitch while the sector is being written.

That should actually be impossible but practice suggests it is not.

|
| And in the ultimate his statement is wrong with drives where
| you can do a true low level format which rewrites the tracks.
| Thats not that common at all anymore with embedded servo drives

I dont think that is the main problem. The problem is that the low level format program needs to know what the number of notches is
and what
the number of sectors is per track within each notch.
All this ofcourse based on the old Format Track command that was abandoned along time ago (ATA-3).

I don't think it is that impossible to make such a program.
I just think that with the automatic reallocation of bad sectors
in place the drivemakers just dont bother to have such a program.

| but was very common with the earlier stepper motor
| drives that got a phenomenon called sector jitter due to thermal
| effects. A low level format would certainly fix bad sectors with them.
|
| > You see, a bloke who clearly knows more than I do about such
| > things in general (he's a PC support professional) recently told
| > me that  one of the ways some modern demo programs "know"
| > whether they've been installed previously is to mark a sector bad.
|
| Yeah, thats been used for many years. Strictly speaking
| thats not a bad sector tho, just one thats been marked bad.
|
| > [And, presumably, put a bit of stuff in that sector to
| > confirm that they've done it when they look again later?]
|
| Can be done that way or just keep track of
| where that phantom bad sector is on the drive.
|
| > If this is so, then maybe there would be a way to recover such lost space?
|
| Yep, in that case just an OS level format will do it.

But not the standard one. That would recognize an existing format
and only clear directories.

|
| > Whether it would be worth the effort is another issue
| > -- I guess it depends whether this scenario is real;
| > and, if so, how many demos you trial. ;-)
|
| You can get a situation where there is some problem in the
| hard drive subsystem that sees lots of sectors marked as bad
| at the OS level, say when you run scandisk etc. Once you fix
| the cause of those bad sectors, an OS level format will recover
| what has been marked as bad but which arent in fact bad at all.

Format /u

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