Dave,
Thanks for responding.
I am using rsync for all backups.
My experience has matched yours in regards to the first full backup of a
large server. The initial backup can sometimes take several days. In
my case, subsequent full backups were/are also taking multiple hours and
sometimes over a day to complete.
After reviewing your comments and re-reading the documentation, I now
understand the difference between the FullPeriod and FillCycle
settings. I've pushed my FullPeriod out to 100 days, and set my
FillCycle to 7 days.
For simplicity, I didn't mention in my OP that I have two BackupPC
servers running at two different physical locations. For critical
client systems, I'm backing up locally and offsite. Since the BPC
servers are independent of each other, occasionally both BPC servers
would concurrently run full backups up the same client system. This was
where I was seeing the most significant impact to the performance of the
client systems. By changing the full backup schedule from 1 week to 100
days, I hope to reduce this situation from happening.
BTW, I'm also running weekly air-gap backups to external media that is
stored offsite. Having critical data backed up both locally and offsite
is reassuring, but no guarantee against an organized ransom-ware attack.
On 9/24/21 3:07 AM, Dave Sherohman wrote:
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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