Letowt Associates

November 10, 1997

BACKUP! BACKUP! HOW DO YOU BACKUP ? (continued)

Dear Colleague:

Last month we talked a lot about backups. There is still more to consider. After you decide the media and method of your backups the next questions pertain to keeping the backups.

How long should you keep each backup? There are two categories of backups; security backups and archival backups. Your regular (security) backups are kept short term and are used for restoring if you lose your hard drive or selected files. Archival backups are taken at critical points in time and should be retained as long as you would be required to retain the documents if they were still on paper.
Accounting records should be archived when you close your fiscal year, and possibly each quarter (ask your accountant) -- these backups should be kept a minimum of three years. A backup which contains "fixed asset" information should be kept for as long as you own the asset(s). If the backup contains "income tax" information, it should be kept for as long as you could be audited (in other words forever).
Where should you keep your backups? You want the backup handy -- but not so close as to be in jeopardy -- so if your system crashes you can get the backup quickly. You do not want the backup sitting in the box that's right next to the computer. If you put the backup in a safe, make sure it is a "data" safe. If you experience a fire or some catastrophe outside your computer, chances are the disk box will be gone too. The simplest thing to do with backups is to take them home or send the set to another location (in another building).
Each backup set consists of the full backup and all of it's related incremental backups or the most recent differential backup.
What kind of a rotation system should you use? NEVER keep just one set of backups -- especially if right next to the computer. Rotate two, preferably three sets. Then if something should happen to your most recent set, you can use the next older. If your baby decides that set is great for teething on, you still have an older set. Going back two or three sets is better that having no backups at all to go to. Most people who back up on tape have five tapes, each labeled with the day of the week, for their security backups. Archival backups will require extra tapes.
What will you have to re-enter if you have to restore? This is tricky. Keeping a backup log will tell you when you last backed up but won't tell you what you've entered since then. If your work is in batches or has some number attached to it (i.e. invoice number), you should enter that number in your log. Then you will know where to start when you restore. If your work is un-numbered keep a folder of what you enter with each backup. After each backup start another folder. If you rotate three backups, keep three folders. When you re-use the oldest backup set, the folder can be emptied (the contents filed or trashed as appropriate). If you keep these folders with the backups you will know what to re-enter after a restore.

Make sure you keep a copy of the backup software safe and on diskettes

Don't forget to clean the tape drive or other device on a regular basis. Tape manufacturers recommend cleaning after each eight hours of use. Make it a weekly habit.

The last, and most important step in your backup procedure is to test your backup. Do not trust the report that says everything is fine. I can not tell you how many times I have seen a person who thinks they are backing up find that the tape is blank. This is more scarey than no backup at all -- you thought you were protected. If you knew you had no backup you would know how vulnerable you are.

Periodically do a restore from your backup. Pick any file that is on the tape and restore it to another sub-directory on your hard drive. If your backup is done overnight, do this first thing in the morning. Then compare the file you just restored to the original. Use the DOS command COMP.

Keeping backups may be tedious, but not as tedious as re-creating everything that was in your computer. Your data is worth more than all the hardware and software you can buy. Your insurance may cover the cost of re-entry, but nothing can re-pay you for your time and aggravation. Seat belts may be uncomfortable, but when needed once...

Some computer acronyms:

Only 781 days to the year 2000

Ricki Letowt

P. S. A good excuse may bring temporary comfort, but solving the problem brings long-term satisfaction.

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