Masonry Magazine February 1994 Page. 52
COMPUTERS FOR CONTRACTORS
What is Backup & Why
Is It Necessary?
A tape backup system is an absolute requirement for any contractor's computer system. A seven tape backup strategy should be considered a minimum, although many companies use a twelve tape monthly set as a supplement to the weekly sets.
OFTEN relate computer concepts to automobiles. The concept of backup can be closely associated with the reverse gear in your transmission. You're driving down the street and for some reason you go past the turnoff. You now wish to return to your previous position of just before the turn. Put the car in reverse and "back up."
A second concept of backup is time travel and the desire to relive the past. To go back in time to a state where everything is back to how it was at some previous point in time. The desire to go back in time is required in order to be able to start over again from that point in time and move forward differently.
Photos are a way you can preserve some past point in time. "Backups" are very similar to photographs, in that they capture exactly how it was with your computer, at some past point in time. The more backups you make, the more choices of how far back to go you have. If you have no pictures that go back far enough, you are out of luck.
The actual backup technique is to read your original data, usually stored on a hard disk, without changing it and then write this same information on to some kind of "off line" external media like a diskette or tape. Each backup will only have the picture of how that original information was at the exact time the backup was made. You can make backups using diskette media.
However, because of its restricted capacity, it often takes thirty or more diskettes, plus your time to sit there and feed each diskette in as needed to make a backup set. Also, the diskettes would need to be numbered in the order that they were inserted into your computer during the backup procedure so that you will be able to insert them in the same order if it's ever necessary to retrieve from them.
A single tape, similar to an audio cassette, can hold hundreds of times more data than a diskette. You should buy a tape unit with a capacity as large as your hard drive storage capacity so that all the data from the disk will fit on one tape. This makes backups an automatic process which can be done while you eat lunch or just need a break. If it's not easy you won't do it. If you don't do back ups, eventually you'll be sorry.
The companion technique to making the backup is to "retrieve" data from the backup media. Retrieval of data is done by reading without changing the backup media and then overwriting the current information on the hard disk with an older version of the information. Data can be retrieved at the file level so as to not always require everything to be set back. Backup everything, retrieve only what is necessary.
The computer system is very reliable and is seldom the cause of your need to "retrieve" the backed up information from one of your backups. Occasionally a power failure will cause damage to either the equipment or data, but use of a UPS (Un-interruptible Power Supply) will eliminate that. The most common occurrence that necessitates retrieval of backed up information is deleting or changing of word processing documents. You want to remove old letters or documents that you don't need any more, and then tomorrow you need them back again. Some times you just forgot to run some report or enter that extra entry and need to go back and redo some work.
When you begin using your computer often or use business software in particular, backup should become an important part of your daily operations. I recommend that you back up data files every day that the system is used. This is done most easily when you utilize seven tapes. Label five of them with the day of the week Monday, Tuesday, etc. Label the sixth and seventh with "Off-Site-A" and "Off-Site-B."
Keep the five daily tapes near the computer and use the one only labeled for today. On Monday, back up to the Monday tape. This will give you several days to choose from. It also gives you a week to realize that, maybe something is amiss and you should go back. It's important that you understand that once you use a tape today, the information from last Continued on Page 54