Shadow disk-driver needed for Moto Sys V/68

[rob hulsebos]

Does anybody know whether a shadow-disk driver (preferable SCSI)
is available for Moto Unix (Sys V/68 R3V[56] ). The driver should control
two disks; all output is written to both disks. Reads are done from
disk #1, until it has reported an error, after which all reads are
done disk #2.
Undoubtedly somebody has done this before, or made an analysis why
this isn't possible under Unix (the problem sounds simple, but actually
it isn't).

Any ideas, pointers, tips, etc. are appreciated.

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Rob Hulsebos
Philips Industrial Electronics
hulsebos at ine.philips.nl