Re: MO-drives, Samba (was Disk space problems)

Richard Shoemaker (rshoe@wwitch.unl.edu)
Thu, 15 Aug 1996 12:47:41 -0500

Just a few quick comments to add to Rudi's regarding the
Tahiti-III, Rewriteable-Optical Drive.

> We have been using a couple of MO drives for over two years on a Sun
> and on an IBM RS6000. They are used daily for system backups, and by
> our users for archiving data. So far, we have not seen any failures (but
> then, archived data are often never read again... )
> The drives we use are Maxoptix Tahiti III which hold ~ 1 GB per disk.
> (I remeber reading about heat problems with earlier models, but cannot
> recall the details.)
> We did purchase software drivers for the drive. Since the media
> is removable,the OS needs to be able to prevent ejecting a mounted
> cartridge(lest you really want to have fun with fsck..). In 94, this was
> not a standard feature (and, even today it may not be..).
> The T-III drives are very fast. There is no noticeable speed difference
> when Processing 1D data. The price for the cartridges is ~ $70, and still
> declining.

I've been using the Tahiti-III, 1.2GB optical drive for about two years also.

1.) There were problems with this drive reported here and there which seemed
to trace to the quality of the power supply. Mine is from Falcon, and they
make _really_ nice cases and use very good supplies. We have in on one
of the Suns, and it's mounteable on all of the systems via NFS.

2.) The version we have _WON'T_ eject the cartridge if mounted. We
occasionally have someone un-mount it on the local workstation while
it's mounted remotely on another one via NFS, and it causes a stale
filesystem handle on the remote machine, but usually the students are
pretty good about checking what others are doing before unmounting.

3.) Since the drive needs to be mounted as root, I use a "sudo" kind of thing
so that the users simply type "cmount" to mount the cartridge, and
"ceject" to unmount the cartridge. Since I started this, the students
don't bug me anymore to find old data...then just come into my office,
find the appropriate cartridge, and work right off the optical disk.
I don't use any "drivers", but just an entry in the /etc/format.dat
file. The things operates aroune 5MB/Sec, and has worked flawlessly
for us for nearly 2 years. With only 1 drive, we can backup everything.
It also works on Macs and PC/s w/ SCSI....in fact, we have the Macintosh
system disks backed up, and can boot off of the Maxoptix drive in
case of a hard-drive failure.

Anyway, I hope some of this was interesting to somebody. Rudi
addressed the cost issue.

Rich

-- 
Richard Shoemaker, Ph.D.                        Phone--(402) 472-6255
Instrumentation Director, Chemistry             FAX----         -6964
Research Associate Professor, Chemistry
University of Nebraska-Lincoln   
URL:  http://wwitch.unl.edu/nmrlab.html