Re: [linux-minidisc] Differences between 1GB HiMD and Standard MD in HiMD-Format

[Michael Karcher <Michael.Karcher@fu-berlin.de>]

Am Donnerstag, den 29.04.2010, 00:14 +0200 schrieb manner.moe@gmx.de:
> Hello,
> as you know, i am testing scsi support for libhimd with libusal.
> I successfully implemented "allow/prevent removal", "himd format",
>  "get disc id",  "get time" and "set time" yet.
> While testing "himd format" and "get disc id" i have found some 
> differences betwenn 1GB HiMDs and standard MDs in 
> HiMD-Format(tested on TDK 80min).
> All tests are made on "blanc discs" (freshly formatted) using
> MZ-RH1 and MZ-NH1.
> 
> 1.  1GB HiMDs have a fixed disc id. It doesn´t change.
Confirmed.

> 2.  "himd format" scsi command doesn´t work on 1GB
>      HiMDs. libusal returns error: incompatible medium installed
>      I think formatting this type on MD can be done using
>      "all track erase" only.
Nearly right. Sony seems to call the operation that fails on 1GB
operations "HiMD erase" (C2/00), and the one that succeeds "HiMD
format" (C2/01). This is because the operation that fails on the 1GB
medium should complete erase everything, including the Disc ID. As you
said in #1, erasing the Disc ID on 1GB media is impossible - so you
can't send the "clean everything command".

> 3.  disc ids on standard MDs changes every time the MD is 
>      inserted. So if i eject a MD and reload the same MD both disc ids
>      will change (the one we get from mclistxx.hma file and the one 
>      we can read per scsi command) but both are the same.
>      (on blanc discs, as i wrote above)
Verified. This really only works for blank disc (as created by C2/00).
These disks are very likely not containing any data, and are usable in
standard MD and Hi-MD for recording in this state. The RH-1 makes up a
file system in RAM when inserting a completely blank standard MD medium.
This made-up file system gets a new ID on every insertion of the medium.

> 4.  sending "himd format" command to Standard MD will only change
>      the disc id we can read per scsi command. the disc id in mclistxx.hma
>      doesn´t change. On reloading both ids are updated to a completely new
>      disc id.
I guess you were fooled by your operating system's cache. I can verify I
have the new disc ID in the mclistxx.hma after remounting the medium in
Unix. As soon as something gets written to the FS (e.g. VFAT access
time), the "shadow FS" from the RAM gets really written to the Disc, and
the volatile disc ID gets fixed until the next blanking.

> HiMDs are marked as "no track", Standard MDs are marked as "blanc disc"
> after initializing with SonicStage or formatting with HiMD-Portie.
> (Format doesn´t work on HiMDs with Portie itself, too, only "track erase" 
> works)
"no track" means that a valid HiMD file system is on the medium, but
containing no tracks. "blanc disc" means a *completely* blank disc.
"blanc disc" can only happen with standard MD media.

See
https://wiki.physik.fu-berlin.de/linux-minidisc/doku.php?do=show&id=himd_device_control for some documentation of C2/xx commands.

Regards,
  Michael Karcher