Choosing a Backup Strategy

Choice of Strategy

How you organize backup depends very much on how frequently the data changes, how extensive these changes are, and how valuable you consider the information. What is essential is that you follow a routine, so that backup is regular and trouble-free.

There are many systematic methods for backing up data on a regular basis. The ten-tape cycle method recommended in this section is very simple to implement. It also maintains several historical copies of the data so that even if one copy is lost you have a high probability of recovering your lost data.

To ensure longevity of your tapes, it is important to follow the tape usage and storage recommendations outlined in Caring for Cartridges. If you follow the backup method described in this section, you should renew your tapes each year. (Since no one tape should be used more than 100 times, annual renewal allows for a number of restores in addition to backups.)

The Ten-Tape Cycle Method

The ten-tape cycle method uses a systematic approach to ensure data security. It involves maintaining a daily, weekly and monthly backup. Every three months the monthly tapes are recycled.

The advantages of this method are:

• Simplicity: It is very easy to recover data.
• Ease of Access: Data backed up any time over the preceding two months can be easily found and restored.

Number of Tapes Needed

If all the data you wish to back up in a single session will fit onto a single tape, ten tapes are needed, plus any additional tapes you may require for archival storage or file transfers.

If you require more than one tape per backup, you will need ten sets of tapes, where a "set" is the smallest number of tapes that will hold a full backup.

Before making a backup, label the ten tapes as follows:

In addition, record on the label the date when you first started using the tape, the name of the system you are backing up, and the backup software used. If you need more than one tape to perform a full daily backup, also record the tape number (such as "Tape 1 of 2").

A sample label is shown below.

Method

1. At the end of each Monday, Tuesday, Wednesday and Thursday, perform a full backup to the tape labeled for that day.
2. At the end of the first, second and third Fridays of the month, perform a full backup to the tape labeled for that day.
3. At the end of fourth Friday of the month, back up to the tape labeled for that month.
4. At the end of the fourth month, recycle the monthly tapes; that is, back up to the tape labeled "Month 1."

For additional security, place each of the Friday and monthly tapes in a fire-proof safe or store them off-site.

Cleaning as Part of Your Routine

Cleaning the drive's tape heads regularly should be an important part of your data security program. Build a cleaning cycle into your backup regime, so that it is not ignored. Use the recommendations in Cleaning the Tape Heads as a guide for how often to schedule head cleaning.

Extending Your Backup Strategy

You can extend the ten-tape backup routine in several ways:

• Use more monthly tapes. Twelve monthly tapes would give a backup horizon of a whole year.
• Build in another more infrequent cycle. For example, you could have a set of quarterly tapes used for a full backup on the last working day of each quarter. These could then be archived indefinitely.