For various reasons (one of which is the quicker backup of SQL server using 3rd party applications), the files of a SQL database have to be defragmented. I am referring to the physical file fragmentation (not internal data/page fragmentation of a database/table) on disk.

Defragmentation utilities, like DiskKeeper, can do the job, but require that SQL server be shut down during defragmentation. As this is not possible in most cases, how is defragmentation accomplished in 24x7 operations? Is it necessary? Does anyone have any experience with this issue?

Thank you,