Gadi Oxman writes:
> Another point to add is that some (newer?) ZIP drives have a jumper
> on them which enables some cheat mode for MSDOS which actually hides
> some sectors from the device driver. That is, block 0 on the drive
> actually moves along with the partition table, and perhaps also the
> reported capacity.
Yes, very good! [It wouldnt be the PC disk drive industry
if there weren't some fake and double-fake involved..]
That explains all reports seen so far concerning size,
geometry, partition table and "FAT bread failed" stuff.
Yesterdays description must be modified:
100MB disks have a capacity of 100663296 bytes, i.e., 196608 sectors
and the 100646912 bytes (196576 sectors) commonly seen is because
the first 32 sectors are hidden.
The hiding is done on some models, not on early models
and not on the very latest either, and that explains why
people report that a disk that is fine on one machine
contains garbage on another, and when written on the other
looks like garbage on the first again.
The hiding removes the first track including the MBR with
partition table. This explains how it can happen that the
same disk has to be mounted as /dev/sda on one machine
and as /dev/sda4 on another.
I'll put this info on some web page.
Maybe we should teach the kernel some of this stuff
so that a poor innocent user doesnt have to struggle.
[Detailed proposals for desired kernel behaviour are welcome.]
Andries
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Wed Mar 15 2000 - 21:00:28 EST