| Fifteen years ago, increasing numbers of people had | | | | as a tape or a dedicated drive. The benefits in cost |
| computers, but their important data consisted of | | | | of disc spanning are easily measurable. For a 20GB |
| small documents and perhaps a few basic programs. | | | | backup set the cost per gigabyte (CPG) will be as |
| To backup all they needed was several blank floppy | | | | cheap as 33c for a DVD-RW disc, compared with up |
| discs and a compression utility. Even a "power user" | | | | to $6 per gigabyte for an external hard drive of |
| might find themselves with two megabytes of data | | | | comparable size. Even for a larger backup of 250GB |
| to preserve. | | | | the optimal cost per gigabyte for external hard drive |
| As we collect more and more important data, our | | | | will be around 80 cents, still twice more than for a |
| backup needs are growing. Like in the past, we still | | | | DVD-RW disc. A large internal drive can have a similar |
| have easily compressible documents, but bulky | | | | cost to a DVD-RW disc, but unless you make enough |
| multimedia files as well, like videos, graphics and | | | | backup sets to fill it, your excess disk space is |
| music. Doubtless this kind of data needs protection - | | | | effectively wasted. In this sense, disc spanning is an |
| the first pictures or a home video of a newborn | | | | attractive and economical option. |
| baby might exist only as binary code on a hard drive. | | | | This table summarizes the cost per gigabyte for |
| If your hard drive fails and there's no backup - unlike | | | | different types of storage media and various backup |
| with traditional film - those digital memories could be | | | | sets: |
| lost forever. Nowdays it's common to find full system | | | | Moreover, disc spanning is simple. All you need is to |
| backups of hundreds of thousands files, ranging | | | | choose the files, obtain some blank discs, and a good |
| between 30 and 120 gigabytes (GB). The problem is | | | | backup program will inform you of the total size, and |
| where to store this data. | | | | how many media units are required for backup. Since |
| There are a number of media types available to | | | | a CD/DVD writing drive became a part of a basic PC |
| most computer users for their backup purposes. | | | | configuration, you don't need to fiddle around |
| Many businesses use magneto-optical or | | | | switching external devices, adding hard discs, installing |
| large-capacity tape drives for their daily and weekly | | | | drivers and playing other "hardware games". The |
| backups. With very high capacities, these drives are | | | | ability to store your backups on discs offsite is also a |
| technically impressive, but the media is usually very | | | | major advantage. |
| expensive. The common backup media for home and | | | | Not only is disc spanning a cheap, simple and flexible |
| office includes CD/DVD discs, dedicated internal | | | | backup method, but it is also one of the most reliable |
| drives and external hard drives that exist in capacities | | | | backup forms today. Modern optical storage media |
| over one terabyte (1TB) with fast Firewire 800 and | | | | has a shelf life of at least 30 years and some |
| USB 2.0 interfaces. Companies like Iomega found little | | | | manufacturers even offer 100 year guarantees. |
| home market success with smaller drives such as the | | | | Compared to an average lifespan of 5-7 years for |
| Jaz (1-2GB) and Rev (35GB) series. | | | | hard drives and up to 20 years for a magnetic tape, |
| Where cost is a priority, a better option for home | | | | optical discs are very long-lived. Disc spanning makes |
| and small business users is often disc spanning, where | | | | it possible that our backups will outlive ourselves. |
| cheap blank media can be used to the same effect | | | | |