Re: cron questions

[On 19 Dec, @01:22, Josh wrote in "[hdup-user] cron questions ..."]
> In Nathan G. Grennan's original post with his cron configuration:
> 
>   http://article.gmane.org/gmane.comp.sysutils.backup.hdup.general/39
> 
> he skips running the weekly and daily on the first of the month and, 
> similarly, skips running the dailys on the days that the weeklys run;
> 
> # Monthly backup
> 0 0 1 * * root /usr/local/sbin/bmonth news
> # Weekly backup
> 0 0 7,14,21,28 * 0 root /usr/local/sbin/bweek news
> # Daily backup
> 0 0 2,3,4,5,6,8,9,10,11,12,13,15,16,17,18,19,20,22,23,24,25,26,27,29,30,31 * * root /usr/local/sbin/bday news
> 
> in the examples/ directory of the hdup tarball the hdup.cron has all of
> these days that were previously excluded, well, included:
> 
> # --- start of new backup season --- #
> 00 02 1 * * root /usr/local/sbin/hdup -q -q monthly host
> # --- the weekly --- #
> 00 04 1,7,14,21,28 * * root /usr/local/sbin/hdup -q -q weekly host
> # --- the daily --- #
> 00 06 1-31 * * root /usr/local/sbin/hdup -q -q daily host
> 
> Now, technically, I could see either as being perfectly valid but... I see
> some problems with the latter (the one included in examples/hdup.cron).
> For example, if the timing of the monthly, weekly, and dailys is set just
> right so that each finishes before the other then you're probably alright.

I think i've seen this happening. Usually cron would send me a mail the next
day complaining "about not being able to find the monthly". Maybe that is
triggered by this race.

> But if not, won't what is backed up be somewhat non-deterministic and,
> worse, possible wrong?  For example, say it is the 7th and the daily
> starts while the weekly is still going -- what will be backed up?  Or,

whenever a backup for a host is running a LOCK file is created. If other 
(incremental) backup are started they will abort due to the LOCK file.
So hdup quits.

> worst case, it is the 1st of the month... the monthly starts...before it 
> completes the weekly starts...and before it completes the daily starts.  
> 
> I suppose I could have one script that I run, starting each right after
> the other -- thus guaranteeing each can't start until the prior one
> completes.  Or I could do it the way that it was suggested by Nathan in
> the first post (which I presume the example cron script is based on).  The
> main difference, I think, would be differing version history.
> 
> Thinking about it I suppose I do want to run all of these from one script
> to (a) make the order deterministic (b) better tweak the ordering for
> version control if I, say, wanted the daily on the 7th to be done before
> the new weekly gets done.

be my guest, I will be happy to include it in crontrib/
This one of those things that should get fiex properly, but (I think) don't 
belong in hdup itself.

> Thoughts?  What are others doing?

keeping my fingers crossed every 1st of the monthy ;-) However, the monthly
dump is _always_ made. And if you use 'always backup = yes' in subsequent
dumps hdup will try to make missing weekly's.... so...

If (for now) changed the times in the example cron script. So that the monthly
has 4 hours to complete.

grtz Miek