On 9/23/21 7:09 PM, Stan Larson wrote:
A few of the servers that are being backed up take many hours to run a full backup, which can modestly impact the end users of those servers. Currently my FullPeriod value is set at the default 6.97 days. Since V4 uses reverse-delta, I should be able to stretch out the FullPeriod to a much longer length of time. What is a reasonable FullPeriod value?
You didn't state what your XferMethod is, but, based on what I've seen with BPC4, this kind of optimization is not necessary when using ssh+rsync backups. I have hosts which took 5-6 days to complete their initial full backups, but subsequent full backups finish in a matter of minutes.
My assumption is that this is because, even though the fulls examine and compare checksums for every file on the host, rsync still only transfers changed data, unlike other transport methods which need to send the entire content over the network regardless of whether it is changed or not.
BTW, FillPeriod is set to 0. My understanding is that the only difference between using FullPeriod and FillPeriod is cosmetic/verbage. Is that correct?
Not really. A full backup and a filled backup aren't the same thing. Every full backup is filled, but the reverse is not the case.
A full backup makes a complete copy of the target host to the backup server (modulo rsync optimizations for unchanged data).
A filled backup has entries in the backup server's index for every file on the target host. This naturally happens with a full, because it gets every file as part of the backup, but an incremental can also be filled by adding index entries for any files which aren't included in the incremental, to produce an index that "looks like" a full backup, even though it isn't. This is basically a way to address the tradeoff you mentioned between backup times and restore times, since restoring from an incremental only needs to look back to the most recent filled backup instead of the most recent full.
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