Holger Parplies wrote:
> Hi,
>
> Boniforti Flavio wrote on 2009-04-29 14:22:36 +0200 [Re: [BackupPC-users]
> Defining data retention periods]:
>
>>>> OK, now the main question of my post: data retention.
>>>> [...]
>>>>
>> In my actual setup when the oldest FULL gets deleted (because it is now
>> older than 4 weeks), do I loose also all the subsequent INCREMENTALS that
>> were done?
>>
>
> would you implement it that way? Then why do you assume it is implemented that
> way? Why don't you just, for once, simply wait and see? BackupPC will show you
> for free.
Even better, you could check the documentation...
$Conf{IncrLevels} = [1];
Level of each incremental. ``Level'' follows the terminology of
dump(1). A full backup has level 0. A new incremental of level N will
backup all files that have changed since the most recent backup of a
lower level.
The entries of $Conf{IncrLevels} apply in order to each incremental
after each full backup. It wraps around until the next full backup. For
example, these two settings have the same effect:
$Conf{IncrLevels} = [1, 2, 3];
$Conf{IncrLevels} = [1, 2, 3, 1, 2, 3];
This means the 1st and 4th incrementals (level 1) go all the way
back to the full. The 2nd and 3rd (and 5th and 6th) backups just go back
to the immediate preceeding incremental.
Specifying a sequence of multi-level incrementals will usually mean
more than $Conf{IncrKeepCnt} incrementals will need to be kept, since
lower level incrementals are needed to merge a complete view of a
backup. For example, with
$Conf{FullPeriod} = 7;
$Conf{IncrPeriod} = 1;
$Conf{IncrKeepCnt} = 6;
$Conf{IncrLevels} = [1, 2, 3, 4, 5, 6];
there will be up to 11 incrementals in this case:
backup #0 (full, level 0, oldest)
backup #1 (incr, level 1)
backup #2 (incr, level 2)
backup #3 (incr, level 3)
backup #4 (incr, level 4)
backup #5 (incr, level 5)
backup #6 (incr, level 6)
backup #7 (full, level 0)
backup #8 (incr, level 1)
backup #9 (incr, level 2)
backup #10 (incr, level 3)
backup #11 (incr, level 4)
backup #12 (incr, level 5, newest)
Backup #1 (the oldest level 1 incremental) can't be deleted since
backups 2..6 depend on it. Those 6 incrementals can't all be deleted
since that would only leave 5 (#8..12). When the next incremental
happens (level 6), the complete set of 6 older incrementals (#1..6) will
be deleted, since that maintains the required number
($Conf{IncrKeepCnt}) of incrementals. This situation is reduced if you
set shorter chains of multi-level incrementals, eg:
$Conf{IncrLevels} = [1, 2, 3];
would only have up to 2 extra incremenals before all 3 are deleted.
BackupPC as usual merges the full and the sequence of incrementals
together so each incremental can be browsed and restored as though it is
a complete backup. If you specify a long chain of incrementals then more
backups need to be merged when browsing, restoring, or getting the
starting point for rsync backups. In the example above (levels 1..6),
browing backup #6 requires 7 different backups (#0..6) to be merged.
Because of this merging and the additional incrementals that need to
be kept, it is recommended that some level 1 incrementals be included in
$Conf{IncrLevels}.
Prior to version 3.0 incrementals were always level 1, meaning each
incremental backed up all the files that changed since the last full.
Chris
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