Hi there,

On Wed, 9 Jul 2025, Gabriele wrote:

I have a problem during remote VM backup, with BackupPc 3.3.2 ...

Yikes!  I think it's a decade since I last used version 3.something.
You really should upgrade, there are good reasons for it in the docs.
Some of them might even have a bearing on your problem.

... The VM is running debian 8 (i know it's old... :), and I'm
backupping it via rsync/ssh. I worked for years, but I guess that
something changed cluster side, and since it's managed I've not got full
control over networking stuff.

It's not clear to me at this stage that you have grounds for blaming
a cluster side change and/or networking stuff but anything's possible.

The problem is that incremental backups stopped working 207 days ago,
and since there are no fresh incremental they have schedule precedence
over full backups, so the only way I have to backup my data is doing
manual full backups.

I can't remember what a version 3 configuration looks like but I feel
sure that you could configure all automatic backups to be fulls.

They simply always fails after 31/32 minutes with the following logs:

?? ?2025-07-09 07:00:10 Started incr backup on xxx.net (pid=3331, share=/)
?? ?2025-07-09 07:31:37 Backup failed on xxx.net (Child exited prematurely)
?? ?2025-07-09 08:00:00 Next wakeup is 2025-07-09 09:00:00

Presumably xxx.net is not really your host.  It's much better to use
"example.net" rather than a hostname for which you have no rights.

Full backup works like a charm in less than 1h 30m:

My guess is that it's just taking a long time to calculate what needs
to be put into an incremental backup.  BackupPC V4 is much better than
version 3 in this respect, it treats fulls and incrementals in a very
different way.

I've searched for logs VM side, but I didn't found nothing intresting.

I would expect the interesting stuff to be in the BackupPC server
logs.  Maybe try increasing the log verbosity in the configuration?
If you set the configuration option

$Conf{XferLogLevel}=2;

(or whatever passes for that in BackupPC V3.2.2 config) you might see
where (i.e. on what file) the incremental backups fail.  I *have* seen
a backup hang when it tried to back up a ridiculously large error log
from the client's X server - and it took a while to find because it
was a hidden file - but that's the only time I've seen that happen.

My suspects are on RsyncArgs config,

What are your reasons for your suspicions?

but I can't figure which are the differencies between full and
incremental backups:
...
...

In my installations, the only difference in the arguments between
incremental and full backups are the addition of '--checksum' for full
backups.  But as this is version 4 that probably doesn't help very
much.  However with

$Conf{XferLogLevel} = 1;

in my 'config.pl' the rsync_bpc command line is logged in the XferLOG.

Following BackupPc configuration for this machine:

$Conf{PingMaxMsec} = 800;
$Conf{FullAgeMax} = 60;
$Conf{FullPeriod} = '6.97';
$Conf{BackupFilesExclude} = {
? '*' => [
??? '/proc',
??? '/sys',
??? '/var/lib/mysql',
??? '/var/lib/php/sessions',
??? '/mnt/data/mysql',
??? '/tmp',
??? '/run'
? ]
};
...
...

I should have thought '/dev' ought to be in there too, and what do you
have in '/var/log'?  As I tend to to keep logs for a very long time I
have a habit of excluding that too.

My questions are two:

[1] How can I debug what's killing my incremental backups? Is it
possible to let them be more ligthweight, maybe letting them finish,
working on RsyncArgs or maybe elsewhere?

If it isn't something as simple as adding '/dev' to BackupFilesExclude
you could try excluding more directories, or, perhaps better, rather
than backing up a share which contains the entire '/' you could define
several shares, with one directory or a few directories from the VM's
root in each share.  Then maybe the problem will only appear in one of
the shares and you can keep on paring down the backed up files until
you get to the bottom of it.

[2] If [1] fails, how can I completly disable incremental scheduling
only full backups?

As I said it's a very long time since I used version 3 of BackupPC so
I probably won't be able to help very much with this.  Can you share
your 'config.pl' file with us?

--

73,
Ged.


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