The Backup Utility

One of the most important tasks for any network administrator is the creation and management of a solid backup and restore procedure.  Microsoft Windows Server 2003 provides many powerful tools that will enable you to perform backups of local and remote data, active directory and open and locked files.

Windows provides a powerful utility for this purpose known as the Backup Utility or “ntbackup”. The Backup Utility will enable you to schedule backups for periods of low utilization, such as during the night, additionally the backup utility also supports Incremental, Differential and System State Backups.

Backup Types

When using the backup utility you must decide which backup type to perform. The different backup types relate in one way or another to an attribute maintained by every file, this attribute is known as the The Archive Attribute.  The archive (A) attribute is a flag that is set whenever a file is created or changed. Once a file has been backed up, the archive bit is cleared until the file is modified. You can also modify this attribute manually.

To do this, right-click on any file, select Properties and then Advanced. The archive flag can then be set by using  the File is ready for archiving control.

Normal Backups

With a normal backup, all selected files and folders are backed up. As each file is backed up, the archive attribute is cleared. A normal backup does not use the archive attribute to determine which files to backup.  Every backup strategy should begin with a normal backup. A normal backup is often the most time and space consuming method. However, restores from a normal backup are the most efficient.

Incremental Backups

With incremental backups, selected files with the archive attribute set are backed up. The archive bit for the file is then cleared. If you perform an incremental backup one day after a normal backup, the job will contain only files that were created or changed during the day.  Incremental backups are the fastest and smallest type of backup. However, they are less efficient to restore. You must first restore a normal backup and then restore, in order of creation, each incremental backup.

Differential Backups

With differential backups, selected files with the archive attribute are backed up, but the archive attribute is not cleared. A differential backup will contain files that have changed since the last normal or incremental backup but not the last differential backup.  Differential backups are more efficient than incremental backups, however they may take up a lot of space. To restore a system, you would perform a normal backup followed by the most recent differential backup.

Incremental Backup Strategy

Monday – Normal Backup

Tuesday – Incremental Backup

Wednesday –Incremental Backup

Thursday – Incremental Backup

Friday – Incremental Backup

In this backup strategy, all files are backed up on a Monday. All files that have changed each day are backed up with an Incremental Backup.

If the server was to fail on a Thursday, then you would need to restore Monday’s Normal backup, followed by Tuesday’s and Wednesday’s Incremental Backups.

Differential Backup Strategy

Monday – Normal Backup

Tuesday – Differential Backup

Wednesday –Differential Backup

Thursday – Differential Backup

Friday – Differential Backup

With a Differential backup strategy, all files are backed up on a Monday. All files that have changed since the normal backup are backed up with each Differential Backup.

If the hard disk fails on the server on a Friday, then you would restore Monday’s Normal Backup, followed by Thursday’s Differential Backup.

Backup Types

With copy backups, all selected files and folders are backed up. A copy backup neither clears or uses the archive bit. A copy backup can be used to copy or backup the computer without affecting a normal backup schedule.  With daily backups, all selected files and folders that have changed during the day are backed up based on the modify date of the files. The archive attribute is neither used or cleared. Daily backups can be used to perform a backup without affecting a normal backup schedule.