Epoch like filesystem

[Michael Sawyer REU]

In article <12795 at vpk1.UUCP> craig at vpk1.ATT.COM (Craig Campbell) writes:
>In article <N~1%AW*@rpi.edu> rodney at dali.ipl.rpi.edu (Rodney Peck II) writes:
  [...]
>>I do... They are about $200 per 5.25" 600 meg platter.  A ten disk juke
>>box costs about $10,000 and is a scsi device.  The problem is lack of
>>software -- this 6 gigabyte thing acts like some sort of large dumb scsi
>>object without the proper software.
>
>The one we have is not a juke box but rather uses removable optical disks
>one at a time.  The disk capacity is 300 meg/side (I think).
>
We have one of the 10 disk jukebox systems on our Sun system, and have
had less than ideal luck with it.

For one thing, it uses a window based program to control the mounting
and dismounting of the disks loaded into the machine.  This means
that, as the software stands now, an operator MUST go to the console
and select which disk is being used.  There is no way to do this
automatically.  (What I would like to see is a method of having 20
mount points (2 sides/disk.  The thing's robotic arm actually flipps
the disk over when you use side B!) per disk.  That way, I can write a
file to /jb1a to get to disk, then /jb6b to use disk 6, side b.  I
realize that this would have to work in a method similar to the
automounter, where the system sits there waiting for a request for one
of the disks, loads it, and mounts it at the appropriate point.  The
hardest point here is when two users ask for different disks.  I may
end up trying to write something to do this, and lock out other users
when anyone has access to the drive.  For what we require, this will
probably be fine...

Also, I don't know how goot the quality control on these devices is at
present.  Our dept. has the jukebox we own as well as the standalone
one disk drive.  According to the people using the other system, they
had a number of problems getting it working, and ours had a defective
eject circuit (I had to take the D*** thing apart to get the disk
out!).  The company blamed it on their drivers, and wouldn't take it
to be repeired for almost a month!

When I did have the disk in the drive, I copied quite a few files onto
it, deleted them, and so forth.  The access time wasn't like a hard
drive by any means, but it wasn't unreasonable either.  (Sorry, I
didn't do any benchmarks.)

I am by no means an expert on this system or Unix (science comes
before system management), but I do have some idea what's going on...
Don't take what I say as the absolute truths.


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Michael Sawyer, Univ of Hawaii Physical Oceanography
(They don't even know I am using rn, so I sure don't speak for UH!)