As a rule of thumb, run Backup on your data after every data entry session that you don't want to risk having to repeat. Depending on your company's volume of work, this may entail running Backup at the end of each hour, day, or week. Backing up may seem time consuming, but it's time well spent compared to reentering your data.

Frequent backups not only guard against loss of data, but also may come in handy if you wish to "back out" a large amount of erroneous data. For example, we have had people call tech support saying that they had posted an entire batch to the wrong period. A backup made just before the batch posting would have allowed them to recover and re-enter that batch into the correct period, without needing to clutter up their GL with correcting entries.

Backups are fastest when the backup file is on a computer hard drive, either the computer running C21 or another computer on the same network. Backing up to a hard drive on another computer on the same network is the most efficient and useful way to do frequent backups, because it is fast and still adds the safety of putting the backup on a different hard drive than the one the company data is on.

Once a backup file has been created on a hard drive on the network, copy the backup file periodically to removable media such as a ZIP drive or a CDRW (Read/Write CD) drive. Although the Backup/Restore commands support backing up to multiple floppies, floppies are no longer a good backup media choice – floppies are too slow and too low-capacity. They often develop errors over time, making the floppy backup unrecoverable.

For additional safety, you can use the rotation method of making backups. With this method, you rotate your Backup location or media by recycling the oldest location. (Put the backup on a network server and/or removable media to avoid losing your data if your hard drive fails.) The rotation method ensures that a substantial portion of your data is protected, even if some time passes before you detect that your current data is damaged. Two examples of the rotation method follow:

• Making three backups for a five-day work week, make a backup on Monday, a second backup on Tuesday, and a third on Wednesday. On Thursday, reuse Monday's backup location to make your daily backup. On Friday, reuse Tuesday's location. On the next Monday, reuse Wednesday's location.
• Making five sets of backups for a five-day work week, back up at the end of every work day. On each Monday, reuse last Monday's backup location to make your daily backup. On Tuesday, reuse last Tuesday's location, and so on.

Following the scenarios above on a network server, create three or five subdirectories with appropriate names for rotating the backup location. If on removable media, label, number, and date your backups so that you can recycle the oldest tapes or diskettes. Tapes and diskettes do wear out; periodically replace old media.