NetBase for MPE Reference Guide

Introduction
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A Different Approach
NetBase approaches shadowing differently from other shadowing products in several ways. First,
since NetBase does not use IMAGE logging, all types of disk files are shadowed, not just databases.
One product can now be used to maintain a complete copy of all application files. NetBase
Shadowing also guarantees that updates occur to the shadow copy in the exact order that they
occurred against the master.
Second, the process that NetBase uses to move data around the network reduces networking
overhead to a bare minimum. Based upon the needs of the particular application environment, the
NetBase shadow process can be configured to minimize the number of network transactions
required to transport updates to the other computer.
Third, if NetBase NFA (Network File Access) is being used, shadowing is integrated with NFA and
NetBase automatically decides when to use the shadow copy and when to use the master copy.
NetBase operates on the principle of master and shadow copies of files and databases. Each shadow
file has a master copy to which all updates for the file are performed. The updates then are
performed on the shadow copies. By using this technique, NetBase can guarantee that all copies
will be exact duplicates of each other.
Shadowing Functionality
NetBase Shadowing is designed to function during all modes of operation and failure. It functions
when posting to shadow copies is interrupted during system backups and during hardware failures.
If the shadow computer is unavailable, the NetBase export process automatically queues all updates
on the master computer until the shadow machine becomes available. The posting process also
queues changes to files or databases that are unavailable. NetBase Shadowing features provide you
with a great deal of flexibility, greatly increasing the functionality of your system and eliminating
unnecessary re-synchronizations.