An Introduction to Tape Backup

If you run a small business, chances are you're saving important files to a server. But what happens when disaster strikes? How are you ensuring that your files won't be lost? Many people fail to realize that the loss of files could cripple their Business. You can insure your office and equipment, but you can't insure files. You can't repair or buy back lost files. Ipso facto, they are lost!

This brings us to the concept of disaster recovery. What is disaster recovery? If you're thinking that disaster recovery is about frantically trying to get back data that's already been lost, then you're already behind the 8-ball! Disaster recovery is about safeguarding your organization's data so that it can be safely restored in event of a crippling disaster. And having an industry-standard file backup strategy is undoubtedly the most important part of disaster recovery.

What you have to do is ensure that all files on the server are backed up to another storage medium -- tape, removable hard disk, NAS device, and so on. Most businesses choose to use tape. Let's look at how you can set up a tape backup strategy for your own Business.

1. Tape -- the perfect backup medium

Isn't tape an anachronism in the age of optical disks, removable hard drives and a plethora of whiz-bang, random-access storage media? Tape is indeed a dinosaur in relative terms, but it's ideal for backup. Tape is slow, but can store a lot of data... one mid-range tape should be enough to backup your entire server. Plus, tape is extremely cheap -- mid-range tapes cost around $20 each.

2. When should you backup?

Typically, tape backup is performed at the end of each day. Just put in the tape and let the backup process run overnight. If your server ever suffers a catastrophic disaster, you have at least saved all your files from the previous day.

3. Tape Rotation

The ideal tape backup solution would involve using a new tape for each backup. This means purchasing a new tape for every day of your business's operations. This is hardly cost-effective for your Business. Tape is cheap, but not that cheap!

This is why we speak of tape rotation. Tape rotation means to reuse tapes from previous backups. The simplest tape rotation scheme is to have one tape for each day of the working week. Tapes are labelled Monday, Tuesday, Wednesday, Thursday and Friday.

You can restore data from any one of the tapes in your library, or in this case, any day in the past the week. This strategy requires only five tapes, but only provides one week's data backup history.

4. Grandfather-Father-Son -- A Case study

The grandfather-father-son schedule is the most widely used method, and involves backing up data in the following way:

* daily -- on the "son tapes"
* weekly -- on the "father tapes"
* monthly -- on the "grandfather tapes"

This system is far more powerful than the five-tape rotation, but requires more tapes.

This strategy provides you with the ability to restore data from the last week, plus any Monday over the last month, plus any month for as many monthly tapes as you have. Variations on this scheme are available, and provide a trade-off between the number of tapes required, and the number of monthly tapes available.

5. Different types of backup

Different types of backups are available in backup software.

* Full -- all files, system data
* Differential -- all files added or changed since the last full backup
* Incremental -- all files added or changed since the last full, differential or incremental backup
* Daily -- all files added or changed on the day of the backup

A Full backup will copy all files and system data to the backup media. It allows for the complete restore of all data from one single tape.

Differential, Incremental and Daily are partial backups are designed to reduce amount of data backed-up to the media, resulting in faster backups. To restore data using one of these backups, the last Full backup tape will also be required, along with any other partial backups since the last Full backup.

6. Tape backup software

At this point you may be thinking that performing tape backup is a complex task. Tape rotations, incremental backups... sure, you can try to do this manually, but this would make the backup process hiddeously dif