3'rd Party Laser Optical Disks

[Michael Piplani]

These will be my final comments on the INTROL 650E Read/Write Many Times 
Magneto/Laser Optical Disk. The reason these will be my last comments is that
we had to return the drive to Introl because we couldn't squeeze it into next
years budget despite my recommendations and the support of my management.  We
thought highly enough of this product that we were going to purchase it, and
I am disappointed I won't have it around-- more 1/4" and 1/2" tape juggling to
do!

The disk drive comes with a driver board which is user installable, and some
driver programs which must be loaded into unix.  The steps to unload the
tape and gen unix are very clear and straight forward.  We didn't have a 
tape drive on our personal iris and were able to unload the tape from a remote
machine with no problem and continue with the installation procedure.  Once
the driver software is genned in unix you plug the drive into the driver board
and you are all set to format, make a filesystem, and mount.  The directions
on doing those operations were very clear, and examples were given.  I was
quit pleased with the level of their directions.  I would feel very confident
giving the whole package to a novice applications programmer and saying: "Here, 
install this".

Introl supplies a set of commands to do operations on the drive, but the
higher level unix commands like mkfs, mount, and tar can be used to make 
the drive visible to the system.  Once mounted the drive is like any other
unix filesystem; you can cp files to it, create directories etc... You can not
tell it's any different from a normal hard disk.  We wrote C code that created
files and then read from them off the disk, and there were no problems, it
behaved exactly the way any disk should.  We display Computerized Tomography
(CT) images in our programs and we saw no real performance degradation from
reading from the slower access optical drive rather then the default drive, 
but I believe the weak (slow) link in this is we use HOOPS software to 
display our pixels not SGI GL software to display pixels.  As far as our 
application was concerned there was no noticeable slow down.


The optical disk can be used a raw storage device, as the target of a tar 
command.  Formatted and mounted the drive gives about 274Meg a side.  Obviously
you can not archive anything bigger then that on a disk side.  Your total
disk storage is well above 500Meg, but you only have access to half of it at
a time.  The reason for this is the disks are double sided, but there is only
one head in the disk drive.  To get to the other side you must dismount, eject
and then remount the disk (if its been formatted and a filesystem is on it
already).  Introl has wisely put a software lock on the eject button so that
a curious user won't punch the eject button on a mounted filesystem and 
destroy a whole filesystem.  Formatting took +45 minutes a side.

The only problems I had were logistical problems in getting the drive up and
running from Introl.  A sales engineer was going to set things up for me and
he was going to bring the drive with him, and ship the cabinet.  Well some 
internals cables didn't make it up here with him, then when they were shipped
to me they were the wrong cables so I had to open the cabinet myself and 
plug them right into the internal connectors.  If I had been a normal customer
I'm sure this wouldn't have happened.  We were the first Personal Iris they
installed one of their drives in and there were problems with driver software
that showed up about 4 days after use.  Introl fixed those problems and the
drive worked very well for us over a 3 week period.  Like I said earlier I
was ready to spend my research groups money on it!.

Michael Piplani
Senior Research Support Specialist
Cornell/Hospital for Special Surgery Program in Biomechanical Engineering

internet: piplani at tcgould.tn.cornell.edu
bitnet:   piplani at crnlimap.bitnet
nynex:    (607)255-9101