Hello,
On 3/30/2006 4:21 PM, Christoff Buch wrote:
Hello,
meanwhile I really tried to get it on my own, but looking at page 135 of
Bacula Manual Version 1.38.5 just knocks me out.
On line one and two it says:
"...... all queued jobs of priority 1 will run before queued jobs of
priority 2 and so on, regardless of the original scheduling order."
While in the last paragraph it says:
"If you have several jobs of different priority, it may not best to start
them at exactly the same time, because Bacula must examine them
one at a time. If by Bacula starts a lower priority job first, then it will
run before your high priority jobs. If you experience this problem, you
may avoid it by starting any higher priority jobs a few seconds before
lower priority ones. This insures that Bacula will examine the jobs in
the correct order, and that your priority scheme will be respected."
I assume the last paragraph applies regardless of jobs running
concurrent or not. Is that right?
If yes:
For me, it sounds like the whole concept of priorities is obsolete and
job order has to be managed all by schedules.
Right?
I don't think so.
See below.
I mean if priorities are only respected correctly as long as jobs are
started (by schedules) in the according order (because bacula needs to
examine them in just this order to be able to respect those priorities
correctly) - what do I need priorities for????
It all depends on the schedules then.
Or did I miss it completely?
Not completely :-)
I'll give an example I use:
I've got the whole Bacula setup allowing multiple simultaneous jobs;
distributed over several storage devices, up to 12 jobs can run
simultaneously.
I schedule all jobs at the same time, to utilize my backup window as
good as possible.
Still I do have some jobs that must be run after the regular jobs:
Database and LDAP catalog backups, and finally a job that shuts down the
backup server.
To ensure proper execution order and to make sure the database backups
are run after the regular filesystem ones - the database server would be
seriously overloaded if those things ran simultaneously - I have all the
regular backups at one priority level, the database backup runs at a
lower priority, and the shutdown job has an even higher priority value.
Result: I have the jobs that must not run simultaneously running in
parallel kind of blockwise.
Coming back to my original concern:
As a pro user I have, as mentioned before, backup-servers each
controlling several streamers of the same type.
The amount of data per day is relatively high.
So I want to be finished with backups in the morning to service my users
with restores if need be.
In other words I want the respective jobs go parallel on the streamers,
not sequentially.
I think I understand why concurrent jobs are not recommended if going on
only one streamer.
Spooling, not priorities would be the option I prefer. If you're short
on disk space you can also limit the number of jobs running
simultaneously on one storage device to one.
But this should be not a problem with two or more jobs each going on an
extra streamer. Right?
Basically, can bacula manage that at all?
I'd say it can, because it does here.
If yes, how should I enable it?
Has this, in my case, to do with "Maximum Concurrent Jobs" at all?
Can I leave "Maximum Concurrent Jobs = 1" in the Storage Resource of the
director's conf? (see my configuration in original mail, please)
That's what I'd suggest if spooling is not an option for you.
Take out priorities completely?
Use priorities very carefully.
IMO, priorities are most useful as an additional means to ensure a
defined job sequence, not to limit concurrency.
Give each job an own schedule and giving them intervals of, say, a minute?
Schedule the jobs in blocks, putting the same schedule into all jobs of
the same priority, and keep some minutes between those blocks.
Arno
Kind Regards,
i. A. Christoff Buch
=====================================
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OneVision Software AG
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IT-Service Lehmann [EMAIL PROTECTED]
Arno Lehmann http://www.its-lehmann.de
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