Backup Strategy

Paul Brennan:10/02/2009 16:47:12

Not long after a business starts to depend on the data held on its computer systems the question of backup is often broached.  The vast majority of businesses have some form of backup system, mostly tape, but data is still lost with alarming regularity due to poor processes being in place.

The worst offence is when a company backs up to a single tape which is permanently left in the tape drive.  If the worst happens, leaving your only backup tape in the same location as your original data is not a great idea.  Tapes are also notoriously inconsistent media.  When new they will work on most occasions, but as the tape gets older its reliability drops; being left with only a single tape is verging on recklessness.

Many smaller companies have what is referred to as a five tape strategy, where Monday – Friday tapes are swapped each day, leaving only one of the tapes in the office at night.  This is better than a single tape strategy, as in the event of trouble, you have five chances of getting a good backup, but it still leaves gaping holes in the backup strategy.

Data inadvertently deleted, or corrupted, which is not noticed and restored for more than a week will be lost forever as the last tape to take a backup of it will be overwritten within the week.

Unfortunately, many businesses only plan a way around this problem after a data loss.  Commonly, this involves buying more tapes to allow one day’s backup per week to be retained for a month, and one backup per month to be retained for a year; quickly jumping from a five to a 20 tape strategy.

If the business impact of a data loss is serious enough to harm prospects or reputation, a 20 tape strategy is a minimum requirement. 

After a company has sorted tape rotation, the next issue likely to demand attention is the rate of data growth on their servers.  Surveys have shown that the volume of data needing to be backed up doubles in less than three years, which often puts the tape drive renewal cycle out of sync with the rest of the technology cycle.  It is usually cheap and easy to add extra disk to a server but a full tape drive cannot have its capacity increased.

As tape drives hit capacity, or simply prove troublesome, an increasing number of businesses are backing up to secure servers online.  An online backup strategy removes the human element of having to change and carefully store tapes, it would normally retain copies of deleted files for up to a year before sending them to archive, and by using out-of-hours broadband, it leverages more use out of existing technology investment.