LBA, but still max 1024 Cyl.

  • Thread starter Thread starter Joop
  • Start date Start date
J

Joop

The problem:
HD is 20 GB Seagate ST 320423A in a machine with Award BIOS dated 1999

The disk has been working correctly, and could be (and was, at that
time) partitioned with PM6

The partitioning made at that time was:
C: primary, active
D,E,F,G: logical drives in extended partition

Now, when trying to modify partitioning, PM 6 cannot access drive and
reports error 105 (Partition table corruption).

I tried another partitioning tool, ie BootitNG, which did see a lot
more about the drive, and I coud even make the primary partition on
the disk 'hidden' , and I could start creating free space.

However, the free space could no longer be reclaimed and was lost!

In order to have a look at the partition table I used Ptedit.
It shows the primary partition correctly (I think) but gives weird
figures for the extended partition.

Moreover, it shows total capacity 4228 MB, with CHS 1024/128/63

Trying to coorect the number of cylinders, it refued to go beyond 1024

In the BIOS I could autodetect the drive correctly, and it shows for
CHS:

2490/255/63 LBA (first choice)
961/128/634 LARGE (second choice)

After accepting first choice, and going back to first BIOS screen, it
indeed shows
USER 2490/255/63 LBA

After saving and exiting BIOS, start Windows 98, shutdown W98, and
restarting, opening BIOS, it shows in first BIOS screen:
4228 MB, USER 1024/128/63 LBA

So, the setting is back to a 1024 Cylinder limit, as if there were no
LBA translation!

In Fdisk: same problem, extended partition not visible/accessible.

I have used Fdisk /mbr several times, no result.

In order to find out if it is a problem related to the BIOS, I
temporarily installed the disk in another, also W98, computer of
almost same age (BIOS date 2000).

Same story allover, complete with proper detection in BIOS, but change
at second boot, to 1024 cyl limitation.
So, apparently, problem is disk-related, not BIOS-related

In Killdisk, de disk is also shown as 4228 MB disk.
Partitions not shown.
So I could not even run Killdisk (accepting data loss) to recondition
the disk to original properties.

Strange thing about this all is that Windows 98 DOES see the
partitions, and the data in them, and does access the data
(read/write).

Using the Seagate on-line test program, it reports the disk as OK with
no problems ,

Any suggestions are welcome!

Joop Klijn
 
Joop said:
The problem:
HD is 20 GB Seagate ST 320423A in a machine with Award BIOS dated 1999

The disk has been working correctly, and could be (and was, at that time)
partitioned with PM6

The partitioning made at that time was:
C: primary, active
D,E,F,G: logical drives in extended partition

Now, when trying to modify partitioning, PM 6 cannot access drive and
reports error 105 (Partition table corruption).
Click to expand...

Serves you right, using malware.
I tried another partitioning tool, ie BootitNG, which did see a lot
more about the drive, and I coud even make the primary partition on
the disk 'hidden' , and I could start creating free space.

However, the free space could no longer be reclaimed and was lost!

In order to have a look at the partition table I used Ptedit.
It shows the primary partition correctly (I think) but gives weird
figures for the extended partition.
Click to expand...

Define weird.
Moreover, it shows total capacity 4228 MB, with CHS 1024/128/63
Click to expand...

Oops.
CHS is limited to 8GB or 1024/256/63, so 1024/128/63 is obviously false.
Apparently such a value below 8GB makes some apps ignore the LBA values.
Trying to correct the number of cylinders, it refued to go beyond 1024
Click to expand...

Which is totally correct as cylinders are limited to 1024 (1023, zero based).
You should correct the heads number to max-1 = 254 (zero based).
In the BIOS I could autodetect the drive correctly, and it shows for CHS:

2490/255/63 LBA (first choice)
961/128/634 LARGE (second choice)
Click to expand...

Those are pseudo CHS values for showing available capacity in (pseudo) CHS.
I think that Large is incorrect with the sectors.
After accepting first choice, and going back to first BIOS screen, it
indeed shows USER 2490/255/63 LBA
Click to expand...

For human consumption (confusion?) only. It won't show that to Fdisk:
LBA 40001850, CHS 1023/255/63
which Fdisk will reduce to 1023/254/63.
Bios will convert 40001850 into pseudo CHS 2490/255/63.
After saving and exiting BIOS, start Windows 98, shutdown W98, and
restarting, opening BIOS, it shows in first BIOS screen:
4228 MB, USER 1024/128/63 LBA
Click to expand...

It reads it from the Partition tables, not the value that will be presented
to Fdisk when you partition an empty disk.

What happens if you don't do the Windows thing but just reboot (reset)?
So, the setting is back to a 1024 Cylinder limit, as if there were no
LBA translation!
Click to expand...

LBA translation is something quite different.
LBA translation is translating CHS into another CHS or into an LBA.
There is no LBA translation above 8GB as there is no CHS above 8GB.
Then there is only LBA addressing (Int13 ext)
That is what the LBA values in the partition tables are for.

The CHS values are only for booting and programs that access via INT13.
It is also used to check partition boundaries.
In Fdisk: same problem, extended partition not visible/accessible.
Click to expand...

Because of the 128 head translation apparently, that causes it to see
it as below 8GB and ignore the LBA values.
I have used Fdisk /mbr several times, no result.
Click to expand...

No surprise there. It ignores the tables, only refreshes the bootcode.
In order to find out if it is a problem related to the BIOS, I
temporarily installed the disk in another, also W98, computer of
almost same age (BIOS date 2000).

Same story allover, complete with proper detection in BIOS, but change
at second boot, to 1024 cyl limitation.
Click to expand...
So, apparently, problem is disk-related, not BIOS-related
Click to expand...

Correct, your partition tables are hosed.
In Killdisk, de disk is also shown as 4228 MB disk.
Partitions not shown.
So I could not even run Killdisk (accepting data loss) to recondition
the disk to original properties.
Click to expand...

Try Zvi Netivs RESQDISK, www.invircible.com
If the partition bootsectors are still in tact it may be able to setup
the MBR from scratch.
Strange thing about this all is that Windows 98 DOES see the
partitions, and the data in them, and does access the data
(read/write).
Click to expand...

It ignores the CHS values and uses the LBA values.
You may be able to just use PTEDIT to set the heads to 254 and then the
other OSes and partitoning apps will likely switch to the LBA values also.
Using the Seagate on-line test program, it reports the disk as OK with
no problems ,

Any suggestions are welcome!
Click to expand...

Moet lukken.
 
Back
Top