Network Data: Copy and Daily Backups
Two of the more specialized network data backup types are copy and daily. These specialized types of backups allows you to apply just the right tool to the problem or need at hand.
A copy backup is similar to a normal backup except that the archive bit isn’t reset when each file is copied. As a result, copy backups don’t disrupt the cycle of normal and incremental or differential backups.
Copy backups are usually not incorporated into regular, scheduled backups. Instead, you use a copy backup when you want to do an occasional one-shot backup.
For example, if you’re about to perform an operating system upgrade, you should back up the server before proceeding. If you do a full backup, the archive bits are reset, and your regular backups are disrupted. However, if you do a copy backup, the archive bits of any modified files remain unchanged. As a result, your regular normal and incremental or differential backups are unaffected.
If you don’t incorporate incremental or differential backups into your backup routine, the difference between a copy backup and a normal backup is moot.
A daily backup backs up just those files that have been changed the same day when the backup is performed. A daily backup examines the modification date stored with each file’s directory entry to determine whether a file should be backed up. Daily backups don’t reset the archive bit.
This option has a logical gap because of the small possibility that some files may slip through the cracks. Someone may be working late one night and modify a file after the evening’s backups have completed – but before midnight – meaning that those files won’t be included in the following night’s backups.
Incremental or differential backups, which rely on the archive bit rather than the modification date, are more reliable.