Re: 2.2.0pre4ac4 and 2048Bytes/sector disks

Daniel Kobras (daniel.kobras@student.uni-tuebingen.de)
Fri, 8 Jan 1999 20:57:37 +0100 (CET)


On Thu, 7 Jan 1999 Jochen Stein wrote:

> From: stein@cs.uni-duesseldorf.de (Jochen Stein)
> Date: Wed, 6 Jan 1999 23:16:31 +0100 (MET)
> Subject: 2.2.0pre4ac4 and 2048Bytes/sector disks
>
> I have a magneto-optical device capable of storing 600MB on
> a 3.5" medium. These mediums have a hard sector size of 2048
> bytes. Previously I have been using a 2.0.3x kernel with patch by
> orschaer@cip.informatik.uni-erlangen.de (has been mentioned on this list)
> to support these disks. I use disks with 1 partition, formatted as ext2
> or vfat.
>
> For test purposes I have booted 2.2.0pre4:
> Linux version 2.2.0-pre4-ac4 (root@gotthard) (gcc version 2.7.2.1) #6 Wed Jan 6 22:45:19 MET 1999
>
> With this kernel (and 2.2.0pre2, 2.2.0pre4 before) I cannot use the 600MB
> disks any more. The partition and disk size are recognized, but mounting
> a fs fails in each case. The mount() system call returns with EINVAL,
> e2fsck fails to find a valid superblock.
>
> Inspecting with dd I found that the boot sector of the vfat partition
> starts after 24 blocks (2048 bytes each) of partition /dev/sdc1. The
> medium was partitioned, prepared and formatted with Fujitsu supplied
> DOS utilities and drivers.

It's a known incompatibility between Linux-2.1/2.2-handling of 2048Byte
sectored media and not only patched Linux-2.0, but also DOS/Win. It'd due
to different views of how long the partition table is supposed to be, if I
recall correctly.

> Medium with 230MB capacity and 512 bytes/sector works. I don't have a
> medium with 540MB capacity.
>
> I would like to avoid saving each medium, reformatting and copying back,
> due to time/space constraints. Boot messages, etc follow below, I can
> provide more info if needed.

I don't know of any fix for this yet, so copying back and forth probably
is your best bet, I'm afraid. I recommend to not use partitions on
640MB-MOs but superfloppies instead, i.e. create the filesystem on
/dev/sdc rather than /dev/sdc1. This will allow using the media with
2.0/2.1, DOS, and 95/98. There's no way I have been able yet to share
my media between 2.1/2.2. and NT4.0 though.

Daniel.

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