File shadowing

There are several different technologies that use the term file shadowing, but the intent of file shadowing within these technologies is to provide an exact copy (or mirror of a set) of data.

For file shadowing to be effective, the shadow needs to exist in a separate physical location than the original data. Depending on the reasons behind the shadow operation, this location may be as close as a second harddrive in the same chassis or as far away as the other side of the globe.

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Wikipedia