Backups

Backups In Brief

• Backups are the most important thing an organisation needs to do.
• Backup procedures must be documented so people know who does what, when and how.
• Backups must be stored offsite.
• Most backups of file servers are done to DAT (Digital Audio Tape)
• The most common professional backup scheme is Grandfather-Father-Son.
• Types of backup are: full (copy everything), incremental (copy only what is new or changed since the last backup), partial (only backing up selected folders).

A backup is a copy of data kept in case the original data is damaged or lost.

Backing up is different to archiving because backing up takes a copy of the original file and leaves the original in place. Archiving is copying the original file to another place offline and deleting the original. Archiving is a cautious person's alternative to deleting files once and for all.

Backups usually not kept for long: they are constantly being replaced by more recent copies of the "live" data. Archives, on the other hand, are usually written once and not updated because the original data is rarely changed after it has been archived.

Backups are too often seen as a boring and paranoid thing to do: a bit like taking out insurance. Many people believe they are Superman, and data disasters are things that happen to everyone else.

I hate to break this to you, but you have not been especially chosen by God. Your data will, one day quite soon, suffer the equivalent of a car crash or heart attack. It will happen. It's your responsibility to be prepared for it.

Backups are serious business in the IT world. Manager know the value of their data, and they would rather sacrifice you to the ravenous Bugblatter Beast of Traal than see their data lost.

An artist's impression of the incredibly stupid but very ravenous
Bugblatter Beast of Traal, whom you would rather kiss than
let your data suffer disaster.

To be useful, backups must be recent and reliable: if you last backed up a week ago and you lost your data, you would have lost a week's work. If the backup turns out to be unreadable, it's as bad as not having a backup at all.

Don't try to save a few cents by choosing cheap backup equipment and media (the stuff the backup is recorded onto, like tape or CD). It's similar to buying a car seat belt from 'The $2 Selt Belt Store'. False economy!

Backup equipment comes in quite a few forms, ranging from floppy disk (unreliable and low capacity) to Quarter Inch Cartridge (QIC) which is very reliable, high capacity and relatively expensive.

It's no good having the best equipment and media unless you actually do the backup properly. This is where a good backup procedure is required. The procedure needs to be:

• documented (i.e. explained in writing so everyone knows how it is done)
• logged (i.e. each backup action needs to be written down after it has been carried out)
• understood by everyone (so Fred can't say, "I thought Sally was supposed to do that")
• tested (if you never try recovering data from a backup, you may have a nasty shock when you discover at the critical moment that the backup is worthless)
• and most importantly, it needs to be carried out! Forgetting to do a backup is an invitation for the Great God of Divine Bad Timing to pay you a visit and destroy your data.

A backup scheme commonly used in organisations is Grandfather/Father/Son, which involves rotating the use of backup media and using different backup types to maximise data security, minimise tape wear and minimise the time needed for backups.

Backups should be stored off site: in other words, the backup should not be stored in the same place as the original data. If a fire took out your file server, it would also take out your backups! Sometimes, backups are copied and the two copies are taken home each night by different people.

A tip for you at home: put all your documents in one location, e.g. C:\DOC. Under that folder, you can have subfolders such as SCHOOL, ACCOUNTS, WEBPAGES, ADDRESSBOOKS etc to store all your creative work. It is much easier to back up a single folder than it is to find a dozen differerent locations on your hard disk where your work has been saved.

BACKUP TYPES

• Full backup - every bit of data is backed up (the alternative is a partial backup)
• Incremental backup- only data that has changed since the last backup is saved.
• Partial (selective) backup - only selected files are backed up (e.g. just the documents folder)