🚀 go-pugleaf

I had a very mysterious hard drive crash and resurrection recently,
and it has me rather mystified.

The drive is a Quantum KA, 13 Gb, and only 8 months old. It has
multiple logical drives in the extended partition (FAT16) and a small
primary partition to allow booting into multiple operating systems.

The problem started when no OSs became bootable, major corruption was
found on the primary partition, and all logical drives in the extended
partition had disappeared. I booted a vanilla WIn 98 version of DOS
from floppy and ran a surface scan from Norton Disk Doctor which found
oodles of bad sectors in the primary partition. 

I resurrected all but the first of the logical drives in the extended
partition and then tried copying essential stuff from these drives to
a second physical drive. At this point it seemed as though there was a
serious problem with the corrupted drive, for although it is a fast
drive normally, it took 4 hours to copy 500 MB, apparently doing
multiple seeks and retries on dodgey sectors.

In the FAT on the primary partition I marked all sectors as unused
(hence good) and ran Norton Disk Doctor again. Even in normal mode the
surface scan was taking ages and was finding bad sectors everywhere.
Thinking it may be Disk Doctor I aborted, remarked the sectors as
unused, and ran ScanDisk with the same results. 

I decided to FDISK the drive and create one FAT 32 partition which I
would surface test and find all the bad sectors. FDISK reported that
the drive had integrity problems but created the drive anyway, and I
set about formatting it. No go, FORMAT.COM (with no switches) reported
that the system area of the drive was stuffed and the drive was
unuseable.

I booted into Windows 98 on the other hard drive and tried formatting
from within My Computer. Low and behold, after about 10 minutes the
program reported that the drive had been formatted. I then ran
ScanDisk from within Windows and it reported that there were no
errors. Not believing it, I went to DOS and ran Norton Disc Doctor's
surface scan, and it found no errors, nor did the DOS based ScanDisk.

I repartitioned to FAT16 and reinstalled the system as was, and it has
had no problem since. I have rerun comprehensive surface scans and
there have been no bad sectors.

So what happened? The bad sectors were real, they weren't an artefact
from a corrupted FAT, I had marked all sectors in the FAT as unused
(and hence good), and the surface scan programs then marked them as
bad. Every surface scan I ran took ages to run, with constant (and
noisy) retries over the same areas. Both FDISK and FORMAT reported
problems. 

Then there was the dreadfully slow transfer of data from the logical
drives. These had no logical problems and they would have been
unaffected by the missing logical drive and the corrupt primary
partition. I had also let the drive return to room temperature a
number of times, and tried it in another machine with identical
results.

To all appearances there were serious problems with the drive, but
somehow things magically fixed themselves, so what happened?

All that I can think of is that perhaps the drive has a self healing
facility and excluded sectors as being bad and then hid them
(rewriting its internal bad track list) when Windows attempted to
format it. The drive does use Smart technology although the BIOS does
not support it.

Anybody got any clues as to what happened? 

Cheers

Ian

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