Ref: 19880010
Title: Restoring a Subdirectory that Has More Than 500 Files
Date: 10/8/90

Copyright 3Com Corporation, 1991.  All rights reserved.

When a file is copied to a subdirectory, DOS must search the entire directory
table to verify that it does or does not exist.  If it exists, then DOS can
locate the file at its current location for whichever operation is requested.
For a Read operation, if the file does not exist, then DOS will report that
fact.  For a Write operation, if the file does not previously exist, then DOS
will look in the file allocation table (FAT) for an available location and
write to it.  As the number of files in a subdirectory increases, the amount
of time that DOS takes to scan the Directory table also increases.

3+Backup uses standard DOS operations to read during a backup and
to write during a restore.  The more files there are, the longer DOS takes to
read the Directory table.  This is evident when you have thousands of files
in a subdirectory and you are performing an off-line restore to a data
partition.  It is actually faster to perform the restore to the data
partitions on line, because the FAT and directory tables are stored in cache
memory.  Cache memory allows significantly faster read times, so the total
amount of time required to read the tables is reduced.
