TAPE STORAGE: TEN TAPE BACKUP PLAN

Your data is one of your business's greatest assets, and a lot can go wrong with data storage. Human error, hardware and software failures, natural disasters, vandalism, virusesÉ these are just some of the factors that can put your data at risk. In fact, human error accounts for about 80 percent of data loss. To make matters worse, the cost of data replacement is estimated at a staggering 100 to 500 thousand dollars per gigabyte. That's why most companies without a reliable back-up system never recover from significant data loss. Follow the three golden rules of data security, and you'll be ahead of the crowd:

• Have a backup plan, and back up every day.
• Have a tape rotation plan. Don't use the same cartridge two days in a row. If your system fails, you might lose both your disk data and the tape data — a disaster!
• Store a complete backup copy off site. Always ensure that a backup, less than a week old, is kept at a different location.

One good plan for small companies uses a five day, four week, three month rotation that uses 10 tape cartridges — 11 if there is a fifth Friday in a month. Larger systems can use multiples of 10 to achieve the same effect. This plan allows for full, differential and incremental backup. In a full backup, all data is stored on the tape. In a differential backup, all data that is changed since the last full or incremental backup is stored. In an incremental backup, all data changed since the last full, differential or incremental backup is stored. The diagram on this page shows the basics:

• Four cartridges are assigned for daily incremental backups (Monday through Thursday)
• Three cartridges are assigned for weekly incremental backups (Friday)
• Three or four cartridges are assigned for full monthly backups on the fourth Friday of each month
• One extra tape is used for an incremental backup if there is a fifth Friday in a month

This type of redundancy, coupled with off-site storage of the weekly and monthly backup tapes, significantly reduces the danger of a data loss disaster.