>>Machines connected in this fashion may also share scsi devices. The
>>read-only cases are trivial, you must take grat care with anything writeable.
>Writeablity would be very desirable! How much does Digital sell their SCSI
>hubs for?
You can share writeable stuff. The problem is software, not equipment.
Basically, only one of the two (or more) machines can use a writeable
partition at once.
So several machines may mount the same partition read-only (or the same
cdrom)
Only one can mount a partition for writing. Other partitions may still
be
read/written by other machines. The machines can take turns writing to
a partition,
but one must unmount before another gets it.
This because each machine have a disk cache, and can't know when the
other is writing to the disk. Cache contents will be wrong after such a
write.
You probably can't snoop a scsi bus, and even that would be open to
races.
If you want both to mount the same partition for writing (or one writing
and another simultaneous read-only) please write a new filesystem where
each machine
ask all the others for permission (and invalidate their cached blocks)
before each write.
Helge Hafting
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This archive was generated by hypermail 2b29 : Fri Mar 31 2000 - 21:00:12 EST