Megneto-Optical drices (SUMM

[Mathew BM LIM]

Thanks to everyone who responded to my request for information on
connecting MO Drives onto Suns. Several people requested that I summarise
this information to the net, well here it is :

===================== My original posting ==========================
>We are looking to purchase one or two Sony eraseble Magneto - Optical disk
>drives for our Sun workstations.
>
>Has anyone any experiences with connecting a (SCSI) Sony M/O drive to a
>SparcStation IPC running SunOS 4.1.1? Is the statement that "support is
>built into SunOS 4.1.1 +" correct? And wil I be able to format and mount
>the drive as if it were a ufs file system? Will I be able to export it via
>NFS?

=================== jwalz at rsg1.er.usgs.gov (Janet Walz)

There are a couple different vendors' versions of such drives attached to
4.0.3 systems around here.  Each vendor supplies a couple additional
kernel modules and format utility (either specific to the drive, or a
generic format replacement).  The details are different for each vendor,
and portability between vendors' formats is problematical (thus far, A's
disks can be read by B, but not vice versa).  If you don't have to
interchange disks with anyone else, just make sure you buy all the same
kind :-).

Once the appropriate things are installed, formatting and mounting the
optical disks looks just like other disks.  I don't recall trying to
export the filesystem, but it should work -- it's the host kernel's job to
make it look like a normal filesystem to everything including NFS, and it
certainly looks like a normal filesystem locally.  They seem to work fine,
but be aware that writing to them is much slower than reading, which isn't
much worse than a regular disk.

4.1 has native support for CD-rom disks, but not optical ones unless
they've been magically folded in as generic SCSI disks without mentioning
it.

============= p554mve at mpirbn.mpifr-bonn.mpg.de (Michael van Elst)

We have these drives on our Sun-3 systems. There are no problems with
SunOS except that you cannot format the media. Nevertheless, the media
comes preformatted so the only thing you loose is the ability to reassign
bad blocks. I'm using a PC/AT to format the media (I wrote a program for
the ST01 controller).

To use the drive you have to label the disk with the format program.  Then
you can create a filesystem and mount the disk.

Since the SunOS driver doesn't recognize removable media (at least with
SunOS4.03) you may get a "UNIT attention" condition whenever you change
the media. You can clear that condition by reading from the raw device
with 'dd'.

====================== Philippe Dax <dax at inf.enst.fr>

We have 2 SMO (Sony Mageto Optical) disks connected to a Sun SS1+.  We use
sd interface directly without others drivers, but a patch is necessary in
the kernel to fix the bug about amovible disks (see BUG in sd(4)).  Robert
Ehlrich from Inria in France has suppleid me this patch (see below).

| From ehrlich at margaux.inria.fr Wed Apr 17 20:10:02 1991
| To: dax at inf.enst.fr
| Subject: Re:  Patch scsi sun4
| 
| <<< = user
| >>> = adb
| ### = comments
| 
| <<<adb -w /vmunix
| <<<sd_findslave+0x178,10?ia	### maybe try more
| >>>_sd_findslave+0x178:            call    _makecom_g0	### or less
| >>>_sd_findslave+0x17c:            mov     %i4, %o0
| >>>_sd_findslave+0x180:            ld      [%i0 + 0x10], %l3
| >>>_sd_findslave+0x184:            ldub    [%l3 + 0x1], %l3
| >>>_sd_findslave+0x188:            srl     %l3, 0x7, %l3
| >>>_sd_findslave+0x18c:            orcc    %g0, %l3, %g0
| >>>_sd_findslave+0x190:            bne     _sd_findslave + 0x1b4  ### patch here
| >>>_sd_findslave+0x194:            mov     %i1, %o3
| >>>_sd_findslave+0x198:            mov     %i0, %o0
| >>>_sd_findslave+0x19c:            mov     %i4, %o1
| >>>_sd_findslave+0x1a0:            call    _sd_winchester_exists
| >>>_sd_findslave+0x1a4:            add     %fp, -0x8, %o2
| >>>_sd_findslave+0x1a8:            orcc    %g0, %o0, %g0
| >>>_sd_findslave+0x1ac:            bne,a   _sd_findslave + 0x37c
| >>>_sd_findslave+0x1b0:            orcc    %g0, %i5, %g0
| >>>_sd_findslave+0x1b4:            call    _kmem_zalloc
| >>>_sd_findslave+0x1b8:
| <<<_sd_findslave+0x190?W 1000000
| >>>_sd_findslave+0x190:            0x12800009      =       0x1000000
| <<<?i		### to verify
| >>>_sd_findslave+0x190:            nop
| <<<$q
| 
| You have to reboot to take effect.
| 
| If it works, make the same patch in /usr/sys/sun4c/OBJ/sd.o

====================== seth at netboss1.trg.saic.com (Seth A. Phillips)

A while ago a vendor sold me a SMO drive for my SUN 1E (it is a SPARC in
6U format).  The salesman said it would work and it didn't so I returned
it and vowed to never buy from that company again (I would mention their
name but they are bankrupt now).  At any rate, I learned a little about
SMO drives.

1) There are two types of formating done on SMO drives:
	Defective Sector Slipping - scans the entire media and maps
		out bad sectors.
	Linear Replacement - writes to disk only the information
		needed to map out bad sectors and thats it (no scanning
		or mapping is performed).  This is what is done on
		the platters at the factory.

2) The SUNOS 4.0.X format program can't do the needed Defective Sector
   Slipping option.  Thus, you end up using the platter as is, defective
   sectors and all.

3) I don't know if 4.1.X has solved this problem.

4) Pinnicle MicroSystems (I didn't buy from them) sells a SMO drive with
   their own formatting program.

5) The drive I received didn't work for other reasons as well (something
   about an incompatability between the 1E SCSI driver and the SMO PCB).

6) I think you can get what you are looking for somewhere, but you need to
   weed through greedy, dumb salesmen that will tell you anything.

================ jws at sv001.sandiego.ncr.com (James Smart)

I worked on the Erasable Optical Driver sold by Artecon. The driver works
on the Sony, Ricoh, and Tahiti Drives.

Support for the Sony is included in SunOS to the point that if a
"formatted" cartridge is inserted, and a "proper disk geometry" is known,
the SunOS format, newfs, fsck, will allow the cartridge to be partitioned
and filesystems created. After this, the standard "mount/umount" commands
treat the cartridge as a normal disk filesystem. Once you've reached this
point, there's no problems with exporting the filesystem (other than the
cartridge can be removed and cause extreme headaches to those that have
mounted it).

NOTE: that special utilities must be created to issue a FORMAT command to
the drive as the standard SunOS format command is incompatible. Defect
list management is also incompatible. It also takes some effort to
generate a disk geometry to properly map the contents of the cartridge.
Take note that SunOS 4.1 (mkfs & fsck) had a problem handling geometries
of 1 head. A patch is available from Sun for this and the patch should
have been included in 4.1.1.

My recommendations for the best optical drive is the MaxOptics Tahiti
drive. The Tahiti has better performance, and supports an optional ZCAV
cartridge format (which is similar to ZBR on standard disks) that has a
capacity over 1GB.  There was also a difference in formatting. The Sony
would not discover as many defects during format, resulting in a larger
grown defect list (and performance hits when the blocks were remapped
during operation). The Tahiti found most (if not all) defects during
format, and rarely grew defects.

 Some Distributors of Erasable Optical Drives in the States are:
     Pinnacle Micro
     Delta Micro
     Artecon
     Andataco
     Apex

================== haydens%bullwinkle at xn.ll.mit.edu (Hayden Schultz)

We buy magneto-optical drives frim Pinnacle Microsystems. I think they may
simply be a VAR for the Sony disks. They're 200 MB per side, Sony makes
the media that we use. It works just like a regular unix filesystem.  NFS
works too.

================== reed at hammer.whoi.edu (Reed)

While I cannot comment on your exact configuration, I can give you this
information. 

I have a sony MO (packaged by a company called Pinnacle, as the REO-650).
While I had a bear of a time getting it to work on my 3/160, when I moved
it to a SS1+ under 4.1, the install was a breeze.  As to m ounting it,
here's the line, right out of my /etc/fstab

/dev/reo0g /usr/export/home/hammer1/reed/reo 4.2 rw 0 0

manual "mount" and "umount" also works.  I have exported this disk to my
local net, and others (on SS1's, ss2's, and IPC's ) have been able to
mount it/ read it w/o a hitch.

I also have used other suppliers of this drive, and again, w/o major
difficulty. 

Hope that helps,

========================= reed at hammer.whoi.edu (Reed)

( in response to my further query about wether he could read / write disks
formatted on drives from different vendors)

No.  As yet, noone seems to have agreed on how to format the disks, so
they all do it differently.  I do plan to experiment some this summer with
ignoring their instructions and attempting to find a least common
denominator, but I doubt that will be in time to be of assistance to you.

Unless for some reason you are stuck on the sony's I would reccommend
looking into the Maxor Tahiti drive.  I believe it has been packaged by a
group called MAXIMUM Storage, and they call it hte Duette, system 7.  Best
part about this, other than speed, compatibility, and size (1 Gb, as
opposed to the paltry 250 Mb you can get per side on a Sony after
formatting), is the fact that it doubles as a WORM drive.  If I didn't
already have the pinnacle, I'd look into one of these seriously.  If you
want more info, their particulars are below.

++++++++++++++++++++++++++ SUMMARY +++++++++++++++++++++++++

1) there are two basic types of drives, ISO standard (eg : Sony) drives
   with a capacity of ~350MBytes / side and a newer Maxtor Tahiti drive with
   a capacity of ~1GByte (and doubles as a WORM drive)

2) Most vendors require / supply a format program for the drive. After
   formatting, the disks may be treated exacatlly as a winchester drive (can
   use mount, umount, newfs, etc.)

3) In general, disk formats are vendor dependant, so you cannot
   interchange disks.

4) SunOS4.0.3 does not support removable media, but there is a patch.

5) The SunOS format program does not support Defective Sector Slipping,
   needed by MO drives.

6) Recommended drive - MaxOptics Tahiti 

My thanks to all those who responded.

Mathew Lim,			| Telephone : +61 6 249 2750
Unix Systems Programmer,	| Fax	    : +61 6 247 3425
ANU Supercomputer Facility,	|