The Why!

Why do we make backups?

Normally, we install a network to share data. Your data is valuable, so consider: "How much would it cost to restore lost data, in case it disappears from the system?" Very often, the value of the data on a system is much higher (maybe even millions of $) than the value of the PC, so an effort must be made to protect this asset. You need insurance (and you pay for it), but hope that you never need it!  It is the same with backups: You make them, hoping that you never need them, but it is too dangerous to live without them. Its not unusual to hear of companies who lost their valuable data, didn't have a good backup, and subsequently went out of business.

What could destroy your data?

• Disk-crashes:
  Your hard drive stops working. Today, disks are fairly reliable compared to 20 years ago (Example: the old HP 7920 removable 50 Mbyte disk drive needed to be recalibrate every 3 months, otherwise the read/writing head would touch the disk-surface and destroy it physically! ), but it still happens.
  
• User/Operator mistake:
  Much more often, data is accidentally deleted by the user/operator and you need a method to get it back.
  
• Sabotage:
  This really happens. An example would be where a computer system manager was fired. The management made the mistake of allowing him to go back to his workstation after giving him the "bad news." He was so angry he reformatted the company's data disk and all available backup tapes!
  
• Water:
  Natural and man made water disasters occur. Each Spring we read about flooding somewhere in the world, even in Utah. Heavy rains could even cause water damage from leaking or caved in roofs.  How about a possible water pipe break in the office?
  
• Fire:
  Buildings burn down. It is very easy to quickly replace hardware, but what about the data?
  
• Theft:
  Systems get stolen. It happens more often than you think.
  
• Viruses:
  This is maybe the most important reason for backups: some viruses are very destructive and delete some or all files from your disk.

The Rules!

Have you ever thought: "Oh, we have a RAID-5 disk-array to protect us against backups" or "I make my backups to my second hard disk".  Well, could these backups protect you against the reasons listed above? Of course not. Please consider the following rules of backing up your data.

Rule #1:
Develop a Backup Plan.

Develop a plan for doing your backups. Before you begin, decide:

• What software you will use to do backups (For Windows systems, I recommend either Veritas Backup or the backup utility included with the operating system),
• What data you will be backing up,
• How often you will be backing up the data,
• What type of media (removeable drive, tape, CD-ROM, Zip, DVD) your data will be stored on, and
• Where the media will be stored.
  

Rule #2:
Make your backup on media (removeable drive, tape, CD-ROM, Zip, DVD) that can be removed and stored in a SAFE place!

It does NOT help if you make backups on tapes but store them all next to the system. A fire would destroy them with the computer. In professional environments, backup media is stored in fire-proof safes, or off site at a storage facility, or in bank-safes.

Rule #3:
The backup-media must be of sufficient size/capacity to allow a complete backup to be made without having to swap the media. This allows for an un-attended backup!

What media should you use to make a backup? If you have to be present during the backup to swap cartridges or tapes every "x" minutes, experience has shown, you will soon loose interest in doing backups ...and then stop altogether.

Some might say: "Well, I make my backup's to floppy diskettes".  With today's modern PC's, which usually have 20 GByte hard drives (or much more), it would take approximately 750 floppies to backup just 1 GByte, not to mention the amount of time involved in swapping diskettes.

Rule #4:
Use multiple backup media so you can rotate backup jobs on different media. Also, plan on replacing older tapes:

You should have multiple backup media (tapes).  For example, one for each day of the week. One tape is not enough. You need at least a few media devices so you can rotate daily backups on different tapes. Each time you do a backup, you overwrite the previous one on the media. Backup media are not 100% reliable, especially tapes. So what happens if a backup media gets a read error and it's your only backup media? You have just lost your only backup! By rotating through multiple backup media, you won't be overwriting your last good backup.

In addition, tapes do NOT last forever. Each time a tape is used, it is flexed by the winding action which will sooner or later damage the magnetic surface, where the information is stored. Tapes should be exchanged at regular intervals.

Note: For home use and for small business usage, a typical backup device will be a removeable hard drive, tape-drive or CD-RW drive.  When more capacity and faster data-transfer is required, DDS - tapes (Digital Data Storage), the computer equivalent of Audio DAT tapes, are often used.

The How!

First of all, there are essentially two types of backup jobs that you should run: Full Data Backup and Differential Data Backup. The full data backup is a complete backup of all data. The differential data backup is limited to backing up only data that is new or changed since the last full data backup. This is particularly important when it comes to restoring data; because, in order to get the most current and fullest restoration of your data, you will first need to restore the most current full data backup job, then restore the updates from the most current differential backup job (assuming there has been a differential since the latest full data backup).

Now, for small businesses with small databases (i.e., a few hundred megabytes), you can use the generic backup utility that comes with the operating system. This is a good backup utility when your database is small and the backup job doesn't need to run very long. However, if it will take longer to backup your data, you will probably want to schedule all backup jobs to run at night (unattended) when the system is least busy. Keep in mind, the backup utility that comes with Windows 98 and ME will not allow you to schedule an unattended backup job. However, if you're running Windows 2000, Windows XP, or Windows 2003 Server, that version has been enhanced so you can schedule backup jobs to run later. Remember, if you can schedule your backup jobs to run at night, do it. And, if you're running Windows 2000 or Windows XP, use their backup utility. For a more robust backup utility with more features, you might want to consider buying a third party backup utility such as Veritas to run your backup jobs. Veritas had many outstanding features, including the ability to schedule backup jobs to run unattended at night.

The typical backup plan for a small business could include running one full data backup job per week, and a differential data backup job three or four nights a week. For example, you could schedule a full data backup job to run each Monday night (say at 9:00 PM), and then schedule a differential backup job to run on Tuesday, Wednesday and Thursday night each week, at about the same time.

If all data is saved routinely in a shared directory/partition on a common workstation, then you would only need to backup that shared partition. However, if everyone saves their work on their own workstations, then you'll need to map the computer with the backup device to all workstations; and of course, you'll need to leave all the workstations on during the nights the various backup jobs are scheduled to run. (Remember, it doesn't hurt to leave your computers on during the night. In principle, you could plan to leave your PCs on 24 hours a day during the week and then just turn them off over the weekend.)

In the scenario above, you would need five media for your full data backup jobs (one for each Monday of the month) and three media for your three weekly differential data backup jobs (one for each evening: Tuesday through Thursday). The full data backup media could be labeled: 1st Week, 2nd Week, 3rd Week, etc. Each month, you would overwrite the full backup jobs from the previous month. You could label the differential jobs as Tues Diff, Wed Diff and Thurs Diff. Each day, you would just need to insert/replace the appropriate media into the backup device of the backup computer so that it would run successfully at night.

An attractive variation to this plan would be to run each of these backup jobs to a file location on the backup computer (rather than directly to the media/tape). And then, copy these backup files to the backup media during the next day. The advantages of this plan is that you would have two copies of each backup job: one on the hard drive of the backup computer, the other on removeable backup media.