Natural disasters, equipment failures, power surges, and deliberate vandalism can cause the catastrophic loss of precious network data. Protecting the data is a primary responsibility of the network administrators (gurus). According to Microsoft, Backup is one of important strategies for preventing data loss or at least recover the data.
NOTE: Microsoft includes many operations which can prevent, reduce, and recover the data. These operations include: Backup, Uninterruptible Power Supply (UPS), and RAID levels. We will very soon discuss all of these topics in the next articles.
What's the Backup
A backup schedule is an essential part of any data-protection strategy. You should design a backup system that is right for your situation and the data on your network.
A number of different strategies can be used in backing up files. One way is simply to copy a file to another drive. Operating systems, however, typically have special backup commands that help you with some of the bookkeeping required for maintaining a systematic backup schedule. Most backup commands mark the file with the date and time of the backup so that you (and the backup utility) will know when a copy of the file was saved last. This is the purpose of the FAT file system's Archive attribute. To determine whether this attribute exists, check the properties of any file on a FAT partition. If the Archive attribute is enables, the file has changed since the last time a backup was done. Some backup techniques reset this attribute, whereas others do not.
Although backups can be accomplished by saving files to a different drive, they typically are performed with some form of tape drive. Commonly called DAT drives, these devices are able to store many gigabytes of information quickly and economically. More over, the tapes are small and portable. Another important step in your backup plan, therefore, is deciding where to store these backup tapes. Many companies choose to make two copies of each backup tape and store one of the copies off-site, thereby guarding against a catastrophic event such as fire.
In addition to the various types of copy commands, Microsoft identifies the following backup types:
Full Backup:
Backs up all specified files.
Incremental Backup:
Backs up only those files that have changed since the last backup.
Differential Backup:
Backs up the specified files if the files have changed since the last backup. This type doesn't mark the files as having been backed up, however. (A differential backup is somewhat like a copy command. Because the file is not marked as having been backed up, a later differential or incremental backup will back up the file again.)
