520 byte sectors - any ideas?

a.vignani@crf.it
Tue, 14 May 1996 07:12:19 +0100


Hi.

A friend of mine got an IBM662 SCSI hard disk coming from an IBM AS/400
system and we tried to install and read it on a Linux system, to no avail.

Seems that these disks are low-level formatted with a 520-byte sector
size, which is correctly recognized by Linux on startup. Unfortunately
this is an unsupported size; Linux allows only 256,512 and 1024-byte
sectors. There are so many >>9 and <<9 in the code I really doubt it
could be easily modified.

Besides, after issuing the messages about unsupported size and removed
device, the Linux kernel panics! The NULLed device is nevertheless
passed to allocate_device() in scsi.c and the system behaves accordingly.
(this should be considered a bug, I think).

We succeeded at least in booting the kernel by removing the SCSI disk
support and using only the generic (/dev/sg*) devices, but then we
have no way of reading data out of the disk; I suppose we should write
a special-purpose driver.

Anybody out there had prior encounters with such disks? Any ideas?

Alberto