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Re: [BackupPC-users] Restrict machine to do full backups Friday night and incremental on weekdays?
2011-03-31 10:14:44
Bowie Bailey <Bowie_Bailey AT BUC DOT com> wrote on 03/30/2011
04:49:32 PM:
> On 3/30/2011 4:11 PM, Jeffrey J. Kosowsky wrote:
> > Timothy J Massey wrote at about 11:55:15 -0400 on Wednesday,
March30, 2011:
> > > Bowie Bailey <Bowie_Bailey AT BUC DOT com> wrote on
03/30/2011 10:52:21 AM:
> > >
> > > > On 3/30/2011 10:16 AM, Scott wrote:
> > > > > Full backups from one machine look like
they are going to take > 12
> > > > > hours, so a night time full backup is not
going to work -
> for this one
> > > > > machine I need it to happen starting Friday
night so it has all
> > > > > weekend to finish (poor connectivity).
All the other machines can
> > > > > stay on the normal default schedule.
Is this possible/how? Thanks!
> > > >
> > > > Two possibilities here:
> > > >
> > > > 1) Start the backup manually the first Friday
night. After this, the
> > > > normal backup scheduling will continue starting
the backup at
> > > > approximately the same time each week. If
it shifts too much, then run
> > > > another manual backup to get it back on schedule.
> > >
> > > This actually works reasonably well. If the
impact of running the fulls
> > > on the wrong day occasionally isn't too great and
you keep an eye once a
> > > week, this works sufficiently.
> > >
> > > Also, don't forget that future fulls are shorter than
the first full if
> > > you use rsync/rsyncd. So if the first one is
taking 12 hours, the
> > > subsequent ones will take less.
> > >
> > > Finally, is a 12 hour backup really that bad for your
> environment? Can it
> > > run from 6 P.M. to 6 A.M., for example?
> > >
> > > In any case, if you absolutely have to make sure you
run them
> on a certain
> > > day...
> > >
> > > > 2) Disable scheduled backups for this machine
and run them from cron
> > > > instead. For example:
> > > >
> > > > # Machine1 backups (3:15am) -- Full on Saturday,
Inc other days
> > > > 15 3 * * 6 /usr/local/BackupPC/bin/BackupPC_serverMesg
backup machine1
> > > > machine1 backuppc 1
> > > > 15 3 * * 0-5 /usr/local/BackupPC/bin/BackupPC_serverMesg
> backup machine1
> > > > machine1 backuppc 0
> > >
> > > I do not recommend *disabling* scheduled backups.
But modify
> it: set the
> > > full backup age to something like 7.97 days and use
the cron entries
> > > described above. That way, if something goes
wrong with the cron jobs,
> > > BackupPC will still initiate a backup. Yes,
it will do this a day late,
> > > but at least you're getting a backup--and maybe the
slowdown
> (or whatever
> > > you're trying to avoid by running it on a certain
day) will letyou know
> > > that there's a problem! :)
> > >
> >
> > Wouldn't a better/more robust solution be to define the blackout
> > period for that machine to exclude everything except for the
weekend
> > -- or everything but Friday night if you just want a single Friday
> > night backup.
> >
> > Just use a host-specific config file
>
> That is basically my first suggestion above.
Except that the blackout periods will prevent the
*incrementals* from running, as I mentioned in another e-mail.
> It all depends on exactly how much tolerance you have for variations
in
> the schedule. If you want no variation at all, then you use
cron. If
> you can deal with the backup time moving around a bit, then you set
your
> blackout periods and manually start the first full backup at the time
> you want it.
On that subject: I have found that, for backup
servers handling multiple hosts, it is better to adjust the blackout periods
to have a relatively narrow open window. I usually only give it two
or three times to start, so a blackout period from, say, 3.5 to 1.5 or
4.5 to 1.5 (to allow it to start at 2 or 3; or 2, 3 or 4 respectively).
That way, there is less opportunity for the backups to interfere
with each other.
The only times I do this rather than let BackupPC
handle it by controlling the number of simultaneous jobs, size of the window,
etc. is twofold: first, some servers are very large and somewhat
underpowered and I only want to start early in the all-night window (otherwise
they'll be running until noon and the users will complain); second,
sometimes I have one or two important servers and a bunch of less important
ones, and I want to make sure that those servers have specific windows
allocated just for them.
I'd still rather use BackupPC for scheduling than
a cron entry: I can easily give it more than one opportunity to run,
and if I do, say, a manual full backup at some other time it works that
into the schedule without a hitch.
Timothy J. Massey
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