The phrase "a back up one" is correct and usable in written English.
It can be used when referring to an alternative option or a secondary choice in various contexts, such as technology or planning.
Example: "In case the primary server fails, we have a back up one ready to go."
Alternatives: "a secondary option" or "an alternative one".
The company says it takes about a half-hour to back up one gigabyte of data -- more than twice the time it takes to transfer the same amount to external drives using U.S.B. 2.0 or FireWire ports (including verification that the backup was successful).
Let me back up one moment to reiterate what an opportunity unemployment or underemployment really does present.
"Look at them boys back up!" one Knick shouted, mocking the tone of an angry coach during a film session.
Everything looks as if 20th Century Fox merely left the fully functioning Nostromo drifting in space until Creative Assembly opened it back up one day and rearranged some rooms and pickups so it has became more like a puzzle.
To get back up one more day, despite the permanent hole in my heart, and do something.
In her collection of essays, Strong Enough To Bend, Judith K. Witherow describes herself as a "back up writer, one of many who stand in the background, providing the harmony and staging the recognition for those whose names are on the covers of the books or the mastheads of the publications".
Try to have two or three different circles of friends, so that you always have back up ones when your best friends aren't around.
The tall, broad-shouldered, easygoing Campbell, now sixty, has been a virtuoso instrumentalist for four decades, backing up one giant after another.
So the driver started backing up, one inch at a time.
Getting through it is about backing up one day's effort with the next and the next, and that's what those massive training camps were about.
