Scientific Operations



UPDATE(VIII)                 11/1/73                 UPDATE(VIII)



NAME
     update - periodically update the super block

SYNOPSIS
     update

DESCRIPTION
     Update  is  a program that executes the sync primitive every
     30 seconds.  This insures that the file system is fairly  up
     to date in case of a crash.  This command should not be exe-
     cuted directly, but should be executed out of  the  initial-
     ization shell command file.  See sync(II) for details.

SEE ALSO
     sync(II), init(VIII)

BUGS
     With  update  running, if the CPU is halted just as the sync
     is executed, a file system can be damaged.  This is partial-
     ly  due  to DEC hardware that writes zeros when NPR requests
     fail.  A fix would be to have sync temporarily increment the
     system  time by at least 30 seconds to trigger the execution
     of update.  This would give 30 seconds  grace  to  halt  the
     CPU.

































                              - 1 -