Aidis.102
net.periphs
utcsrgv!utzoo!decvax!duke!mcnc!idis!dan
Tue Mar 23 22:20:37 1982
Using SMS floppy disks on a VAX


Our installation is getting a Scientific Micro Systems floppy
disk system (FWT1127S) for our VAX.  It is RX02 compatible and
has an extended mode that provides on-line formatting and supports
double sided diskettes and several IBM formats (i.e. larger sector
sizes) that increase storage capacity by 23% (up to 2464 blocks
per diskette).

There are supposed to be six other vmunix sites that have ordered
similar equipment.  Does anyone have experience using these drives
on a VAX 11/780 unibus?  Has anyone developed a driver that uses more
than the RX02 compatible features?

We intend to place the floppy drive in a terminal room so that
our users will have convenient off line storage and we can
assign student disk quotas ruthlessly.  Has anyone considered
the implications of installing such a device on a unix system?

There must be a mechanism for allocating drives.  If we wish to
allow user file structures (and we do), there must be a
privileged program for mounting diskettes and the driver must
prohibit special file I/O on a mounted diskette.  There may
still be ways for a user to sneak a setuid file past the
mounting utility.  Therefore we will probably modify the kernel
to ignore setuid bits from the floppy block devices.
Cached blocks from dismounted diskettes may be a problem.
Must the length of the diver's active buffer queue be limited
to avoid filling up the system cache with write behind blocks?
Have I forgotten anything?

               Dan Strick
               ...!duke!mcnc!idis!dan

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