FTP Checkpoint

3 May 88 13:02 EDT

The FTP implementation on the Honeywell mainframe done for the World-Wide
Military Command and Control System (WWMCCS) implements and uses checkpoint/
restart. It also lets you begin a transfer, leave, and check back later on
status. They used to move huge files in the mid/late 70's and restart was
essential for operational, not cost, reasons, because the system didn't stay
up long enough to complete very many transfers. The checkpoints were based o
time, not number of records transfered, because the variability in throughput
was high, and minimizing the amount of lost time was the important issue. I
think 5 minutes between checkpoints was the default.
  All this continues to work as we speak -- of course the protocol it is
running over is NCP......


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