On Thu, 22 May 2003 at 9:12pm, Per von Zweigbergk wrote

> What happens if you don't? Will it e-mail you pestering you to change 
> the tape, forcing you to do two tape runs on one day?
>
> Or will it simply drop that run, noting the problem... i.e. just fail 
> gracefully, and try again the next day, effectively delaying the backup?

It depends.  I have cron run 'amcheck -m' every day at 4.  That will email 
the operator if it doesn't detect a tape (or detects any other problem), 
but otherwise won't bother anybody.

If there's no tape when amdump runs, it will back up as much as it can to 
holding disk.  The next day (or whenever you get back), you run 'amflush' 
to put stuff on tape.

> The reason I ask is, what happens in a school holiday, when nobody is 
> on site working the backup units? Of course, the "proper" solution is 
> to disable the cron job during school holidays, but what is someone 
> forgets?

I always just leave mine running, and may have to do multiple amflushes 
when I get back.

> Tapecycle == amount of tapes. Has to be a multiple of dumpcycle for 
> optimal conditions. (?)
> 
> Dumpcycle == amount of tapes in a "cycle"... i.e. one extended backup 
> dragging on several days. Each tape will typically contain one or more 
> full backups, as well as incremental backups of most (all?) filesystems.

Almost.

dumpcycle = maximum length of time between level 0s of any particular DLE.
runspercycle = number of times you'll run amdump per dumpcycle
tapecycle = number of tapes you have.

You should really have at least 2 * runspercycle (* runtapes) tapes -- 
that'll ensure you always have at least 2 full dumpcycles on tape.

-- 
Joshua Baker-LePain
Department of Biomedical Engineering
Duke University