When most people think of a backup strategy they think about tape rotation and backup schedules. While these are important parts of a backup strategy they're not the whole story. As an organisation begins to assimilate more and more servers, a reliable backup strategy becomes more challenging. Instead of one tape drive that backs up the entire network, libraries become necessary. Instead of doing one backup job and schedule, you need several. Here are four fundamentals for developing your backup strategy.
Plan for growth
Most organisations have begun to start monitoring their disk storage needs. While disk storage is cheap, the cost of maintaining all those files, including archives and backups, starts to become a real expense. When an organisation plans its disk needs, it needs to review its growth and determine how much extra disk space will need to be purchased over the next year.
But here's the rub. Adding more disk space is relatively easy. You just add new drives to the disk array or you swap out smaller disks for larger ones. The process takes time but it's relatively transparent. Upgrading tape capacity isn't so easy for most organisations.
The hard part to stomach is that the cost of your tape drive system may exceed the direct costs of your disk expenditures. Because of expensive libraries, drives, and cartridges, backing up a system can often cost more than the disk drives for an organisation. Because of this, it's difficult to make the up-front investment necessary for scalable growth — but it's a decision that will have a substantial impact on the amount of backup protection that is purchased next year. When developing your backup strategy don't forget to develop a strategy for containing your overall disk storage requirements.
Keep it simple stupid
The cornerstone of a backup strategy is the men and women who change the tapes in the drives on a routine basis. Whether you have a library that holds dozens of tapes or a single high-capacity backup drive, the tapes must eventually get changed. Because changing the tapes relies on humans it is, frankly, one of the more common areas for a backup strategy to fail. Your tape rotation strategy should be simple so that the potential for mistakes be minimised. The more complex the strategy, the greater the opportunity that it will be messed up.
Although backup programs today support all kinds of media retention policies, the reality is that most people really only understand simple rotations. Doing daily tapes, weekly tapes, and monthly tapes are often effective. This backup mechanism is the venerable grandfather-father-son rotation that most in the industry have used. The beauty of this rotation scheme is that sets of tapes can be labeled for insertion on a specific day which is marked on a calendar. The tapes that are inserted on that day are marked and all of the other tapes are removed.
If something does go wrong with the rotation it's easy to review the calendar and the tapes and determine what happened and how to get back on track. Trying to sort out a more complex tape rotation scheme can be difficult — even with the help of software.
