Really, redundant file servers

[jans at stalker.UUCP]

In article <12959 at sun.uucp> dss at sun.UUCP (Daniel Steinberg) writes:
>In article <2592 at phri.UUCP> roy at phri.UUCP (Roy Smith) writes:
>>
>>	How hard would it be to incorporate a "shadow server" mode into
>>NFS?  Imagine 2 servers serving the same file system...
>
>In many ways it is simpler to have a physical disk shadow than a
>filesystem shadow...

Simpler, and MUCH more efficient.  The Tandem NonStop fault-tolerant
computers provide parallel writes, but split seeks on reads.  I.e.: One
disk is assigned cylinders 0-405, the other cylinders 406-811, reducing
the average seek time by a factor approching two.  The actual improvement
is tempered by accelerated seeks, out-of-area writes, and non-locality of
reference.

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