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Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!crdgw1!uunet!xstor!root
From: root@xstor.com (Superuser)
Newsgroups: comp.periphs,comp.periphs.scsi
Subject: Re: R/W optical disks (again!)
Message-ID: <1991Mar18.224333.12869@xstor.com>
Date: 18 Mar 91 22:43:33 GMT
References: <1991Mar6.171838.26771@news.larc.nasa.gov>
Organization: Storage Dimensions, Inc.
Lines: 73

In article <1991Mar6.171838.26771@news.larc.nasa.gov> kristi@arbs1.larc.nasa.gov (Kristi Skeens) writes:
]
]I posted here recently asking for info on fast writing r/w
]optical disks. I got several responses and appreciate them all.
]Now I have another question: I am running UNIX on a PC, are there
]any optical disk systems that are compatible with this set-up? I w
]as told by someone at Maximum Storage that this animal did not exist.
]
]Also, could some kind soul give me a brief overview of optical disk
]systems or steer me in the direction of good general information?
]I am a neophyte, so anything would help.
]
]TIA,
]ks 

Kristi,
Several companies offer R/W optical technology for the PC style
UNIX systems. The current offerings are primarily drives called
"Magneto Optical" (MO) drives. The primary manufacturers of these
drives are Sony and MaxOptix (a Maxstor subsidiary).

Media for these drives come in two flavors, glass and plastic. They
each have advantages and disadvantages. Plastic is lighter and spins
up and ready faster than glass. It is also less expensive. Glass
has better temperature tolerance and better capacities.  The Inter-
national Standards Organization (ISO) has specified a format that
provides 650Mb per cartridge. Note that this is the unformatted
capacity. Also note that half is on one side/ half on the other.
This means that only 325Mb (unformatted) is available at any given
time.

The MaxOptix drive (sometimes referred to as the 'Tahiti') allows
for 1Gb unformatted on glass cartridges. It can also read and
write the ISO format cartidges.

The Sony drive(s) only support the ISO format. 

Please pay attention to power, RF, and cooling for MO drives. They
require more power and cooling than a typical magnetic drive. The
typical PC doesn't provide enough cooling for the MO drive and 
some don't have enough power. MO drives put out lots of RFI. 
The recommendation here is to get an external box/subsystem that
is designed for MO use. Several vendors provide this.

Almost all MO drives use the SCSI interface. If you are not familiar
with this, please ask... There are many experts who monitor this
group.  

Compared to the latest hard disks, MO drives are slow. However, 
they are fast enough that some folks do actually use them as a
boot/root device.  Actual throughput on applications is around
70-100 Kbytes/sec. This compares to 200-400 Kbytes on the typical
ST506 kind of disk. The actual speed is dependent on the drivers
being used and the type of filesystem being utilized. Please note
that this was the speed of the leading technology only a year or
two ago.

Probably the most important thing to watch for is how well supported
the optical drive is by your vendor or OS. Is removable support there?
Does the operating system understand optical or does the drive have
to be jumpered to 'fool' the operating system. Almost no PC UNIX
vendors support optical in the native OS.

At this point, please allow me the liberty of plugging our products.
We offer complete subsystems (Optical and Magnetic) for DOS, UNIX, 
OS/2, Macintosh, and Novell. These come complete with full driver
support. If you would like to know more about our products, please
mail me or call. I'll be happy to put you in contact with the right
person to answer your questions.

Bill Brothers
Product Engineering Mgr.		Storage Dimensions, Inc.
billbr@xstor.COM			(408) 879-0300