[From Search SQL Server
One of the toughest things about managing a big database is the backup window: The bigger a database gets, the longer SQL Server backups take. Ironically, larger databases like data warehouses are also the ones that want the smallest nightly maintenance windows because they're desperate for more time to load the data.
Storage area network (SAN) database snapshots give DBAs the ability to bypass the backup window altogether and perform backups inside the SAN instead of doing it at the operating system level.
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