As I've said before... do NOT rely on all your backups for an
entire month being on one tape. If the tape breaks on the last
backup of the month, the net result is that you'll have no backup
at all. I currently have Volume Use Duration set to 5 in my
environment and I feel like that's even a little risky but I haven't
fully ramped everything up yet. It may seem like a waste to buy
many LTO-4 tapes for each month but you'll wonder how you could
worry about such a small cost ($40 / tape or so) if you wind up
getting stung by a problem like that. The cost per gigabyte goes up a
lot if you consider that you're only putting 200 GB vs 800 GB on some
tapes but whenever thinking about backup strategies, don't forget to
think about the cost of lost data as you weigh relative factors.
And this number will also probably be small compared to the price of
the changer.
How big is your changer? Is it big enough to always just keep a
group of tapes in plus a few scratches? If that's the case, then
my suggestion is just pull out tapes marked Full or Used and bring
back new scratch tapes as frequently as you can manage. After getting
your settings right you can do it almost blindly whereby you just
bring back the oldest scratch tapes (i.e. use the scratch pool).
Volume Use Duration will apply to each tape not each "tape group".
I like to use just one pool for all my backups of a certain "class
of service" and let bacula handle all the management.
Don't bother with one pool per month. You'll find that something will
happen (holiday, network error, whatever) and bacula will get out of sync
eventually anyway.
> Normally I would set up with weekly tape group rotations and Daily pools
> so that for a work week, I would have maybe 3 tapes for each day and
> more tapes for the full backup on Fridays. I would also have things like
>
> Volume Retention = 17d
> Volume Use Duration = 2d
> Maximum Volume Jobs = 4
>
> to allow for tapes not inserted on time (Volume Retention slightly less
> than 3 weeks, etc.)
>
> Now I am considering a monthly group of tapes with maybe 3 groups of
> rotating tapes and that causes me all sorts of confusion with the ideal
> setup. I have an LTO-4 tape w/ changer so I am dealing with groups of
> tapes for each rotation.
>
> My thought is that the first backup for each cycle would be a full
> backup. Then the rest of the month would be an incremental backup.
>
> I think I could probably use maybe 61 or 62 days for 'Volume Retention',
> maybe 29 days for 'Volume Use Duration' and some very high number for
> Maximum Volume Jobs so that each workday's incremental could just keep
> getting written to the same tape until it fills.
>
> I think my questions are:
>
> - If I target the first day of the month to start a new rotation for a
> set of tapes, this date may come over a weekend or a holiday but I
> gather I can set the 'Maximum delays' to an appropriate value but is
> there a better way to handle this?
>
> - How can I ensure that the previous months tapes status is changed to
> 'used' so that bacula doesn't ask for a tape from the previous month?
>
> - Do I have to segregate the 'Pools' for each monthly set of tapes? Is
> there any reason to segregate the 'Pools' for those that are Full or
> Incremental backups when I want to keep the entire month together as a
> group for swapping in/out of the changer?
> - Does this seem correct...
> Schedule {
> Name = "MonthlyCycle"
> Run = Level=Differential Pool=Backup 2-31 at 9:30pm
> Run = Level=Full Pool=Backup 1 at 9:30pm
> }
>
> Craig
>
>
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