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

[Mark Verber]

> In theory, there is a risk if directory affecting operation
> are done just at the wrong time (between passes of dump), but in
> practice I have never heard of an actual problem occuring.  If you
> can't take that small/really tiny risk then go to single user mode.
> Otherwise, in practice, you most probably will never see a failure,
> especially if you do your dump overnight.

I have in practice seen a dump corrupted when run on an active file
system.  I will admit that I have only seen this happen only once over
a 10 year period.  But if that one time failure has something critical
on it you do not forget the experience of having users out for your
blood.  I certainly never intend to repeat that experience.  My policy
has been to run incremental backups on a active file system late at
night (to exebyte's from cron), but when I do level 0 dumps I drop to
single user.  This is pretty painless for me since those things that
I regularly dump at level 0 will fit on a single exebyte tape so I
have my servers shut themselves down automatically in the middle of the
night, run dump, and then come back again to multi-user mode.

Cheers,
Mark