Which method should you use?

Depending on your needs, examine each method and decide which is best for your company. For example, a full backup is easiest to restore, since your most recent data is on one tape. But full backups take longer to perform than incremental or differential, and if you have a large amount of data to be backed up, it may be unreasonable to perform full backups every day. Some of the questions you should be asking yourself when deciding upon a backup strategy are:

• how much data gets backed up?

• what percentage of data in my set changes day-to-day?

• how long do I want the backup to take?

• if I have to recover files, how long do I want to spend restoring?
  

If you have large amounts of data to be backed up every day, but your restore needs are not as pressing, choosing Incremental backups daily may be your best solution.

Incremental backups only include files that have changed since the last full or modified backup, and in general is considered the quickest method for backing up. However, if you need to recover a client, you will need the last full backup, and all incremental backups after that. For example, if you perform full backups on Monday, and incremental backups Tuesday through Friday, and on Friday you need to restore a host, you will need Monday's full backup and Tuesday through Thursday's incremental backups to recover all the files for that host.

Incremental backups are only available for NetWare servers and Windows clients.

``Differential'' may be for you, if you want to restore files quicky, using less tapes

On the other hand, if you want to quickly recover files from only one or two tapes, and you don't care as much about how long the backup takes, choose the differential method. Using the same example as above, on Friday you would need Monday's full backup, and Thursday's differential backup tape to recover all the files for that host. This is because Tuesday's differential tape contains files that have changed since Monday's backup, Wednesday's differential tape contains files that have changed since Monday's backup (thus, all the files from Tuesday's tape will also be on Wednesday's tape), and so forth. Your tape requirements increase the further you get from the last full backup.