Why idle backups?? (was Re: Looking for shell script for backup on BSD 4.3)

[Shiping Zhang]

In article <32749 at sparkyfs.istc.sri.com> zwicky at quetzalcoatl.erg.sri.com.UUCP (Elizabeth Zwicky) writes:
>
>Purdue modified dump if at all possible, and you should give serious
>thought to running level 0s in single-user; you can do this
>automatically in the middle of the night by using the same sort of
 ^^^^^^^^^^^^^
>trick that fastboot uses, creating a magic file that the rc files
>look for in the boot process to tell them to do backups.
>

I have seen this suggestion more than once on this news group.
But I don't know how. One question I have is about the tape changes.
Certainly one tape is not enough for a zero level backup.
How to get away with this problem?  Thanks for any enlightenment.

-ping