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NetBackup System Administrator’s Guide - Windows NT Server
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• For a cumulative-incremental backup, NetBackup backs up files that have
the archive bit set, but does not clear the archive bits after the backup. This
allows the next cumulative incremental to back up not only changed files,
but also files that were in this cumulative incremental.
If the Perform Incrementals Based on Archive Bit box is clear, NetBackup
includes a file in an incremental backup only if the file's datetime stamp has
been changed since the last backup. The datetime stamp indicates when the file
was last backed up.
• For a full backup, NetBackup backs up files regardless of the datetime
stamp.
• For a differential incremental backup, NetBackup compares the file's
datetime stamp against the last full or incremental backup.
• For a cumulative incremental backup, NetBackup compares the file's
datetime stamp against the last full backup.
If you install or copy files from another computer, the new files retain the
datetime stamp of the originals. If the original date is before the last backup
date on this computer, then the new files are not be backed up until the next
full backup.
Determining Backup Media Requirements
To efficiently manage your backup environment, you must know the amount
of media that is required for both daily and long-term use. The daily
requirement must be known to ensure that enough tape volumes and disk
space are available for each backup session. The long-term requirements are
necessary to assess costs for acquisition of new media, storage devices, and off-
site storage (if required).
For daily requirements, you must first determine the approximate amount of
data in the files that you will back up to each type of media each day. Then,
you can check the Media Summary report to verify that enough media IDs and
disk space are available.
For long term planning, you must also consider the following:
NetBackup 3.2 System Administrator's Guide for Windows NT
NetBackup 3.2 System Administrator's Guide for Windows NT
