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Tech Tip: 4D Backup: Backup vs. Mirroring
Published On: June 23, 2000
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Performing a local backup has many advantages but it has two major drawbacks:

During the backup, any access to the data is delayed until the backup is complete.

Since the backup is performed by the machine that is actually running the database, a hardware problem on that machine may affect both the original copy of the database and its backup.

If you want to avoid those drawbacks, you should consider setting up a mirror on a different machine. In addition to the obvious security gain provided by the new machine, using a mirror does not require the data to be locked when the backup is performed. With a mirror, the backup is executed on the mirror machine and the database automatically closes its log file and sends it to the mirror. Clients can therefore keep on working on the data with very little slow down in their activity.