What is Backup?
Windows 2000 and higher versions provide a backup utility, called Backup, for creating backups on local and remote systems. You can use this utility to archive files and folders or restore archived files and folders.
You can access media pools reserved for Backup and access remote resources through My Network Places. You can also create snapshots of the system state for backup and restore, schedule backups through the Task Scheduler, and create emergency repair disks.
TYPES OF BACKUP
The basic types of backups are:
Normal/full backups: All files that have been selected are backed up, regardless of the setting of the archive attribute. When a file is backed up, the archive attribute is cleared. If the file is later modified, this attribute is set, which indicates that the file needs to be backed up.
Advantage :
- Provides a complete copy of all your data
- Makes it easy to locate files that need restoring.
Disadvantage :
- Takes a long time and maximum space on backup media
- Redundant backups created, as most files remain static.
Incremental backups: This is designed to create backups of files that have changed since the most recent normal or incremental backup. The presence of the archive attribute indicates that the file has been modified and only files with this attribute are backed up.
When a file is backed up, the archive attribute is cleared. When the file is modified, this attribute is set, which indicates that the file is backed up.
Advantage :
- Uses the least time and space as only those files changed since the last backup are copied
- Let’s you back up multiple versions of the same file.
Disadvantage :
- Makes the job of restoring files fiddly, as you have to reinstall the last full backup first, then all subsequent incremental backups in the correct order
- Also makes it hard to locate a particular file in the backup set.
Differential backups: Designed to create backup copies of files that have changed since the last normal backup. The archive attribute indicates that the file has been modified and only files with this attribute are backed up. A backup of those files which have to change the last full since the backup. Should be performed at regular intervals.
Advantage :
- Takes up less time and up space than a full backup
- Provides for more efficient restoration than incremental backups.
Disadvantage :
- Redundant information stored, because each backup stores much of the same information plus the latest information added or created since the last full backup.
- Subsequent differential backups take longer as more files are changed.
Copy backups: All files that have been selected are backed up, regardless of the setting of the archive attribute. Unlike a normal backup, the archive attribute on files is not modified. This allows us to perform other types of backups on the files at a later date.
You can choose from any of the three different backup methods. Most backup strategies use a combination of two or three of these methods.