tar backup - inconsistent snapshot of repository

[Geoffrey Hird]

Suppose:

1. We are making a tar of the CVS repository as a backup.
2. We do not lock users out from writing to CVS, as the process
takes 3 hours and there are users in multiple time zones.
3. A user commits a file during the tar so that the CVS bookkeeping
is inconsistent with the committed contents.

I'd like to know what are the consequences from the following
point of view.  Suppose our CVS server dies (irrecoverable disk
failure), and we switch to a backup machine, and restore the
repository from the tarball of the previous day.  Obviously
we've lost a day's work, but that's not the end of the world.
If the snapshot fails badly, it *is* the end of the world.

How bad can things get?  Can this make CVS crash?  Will CVS
continue to function, but give error messages about just the
directory in which the file in question was committed?  Will
CVS function with no error reporting, but simply show the
repository incorrectly from users' perspectives?

I'd appreciate any help.

gh