Hi there,

On Fri, 17 Jul 2026, J?r?me Aug? wrote:

I'm currently configuring a new bare-metal BackupPC v4 server with Ubuntu
24.04 packages (backuppc `4.4.0-8build1` + backuppc-rsync
`3.1.3.0-3ubuntu1`), for replacing our aging BackupPC v3 on Ubuntu 20.04,
and I'm experiencing various errors and silent corruptions.

I'm in touch with another user who is having trouble with any version
of rsync-bpc 3.1.3.x.  In that case it appears to be a resource issue,
but until now it has seemed only to happen in a particularly odd set
of circumstances that include Docker on top of layers of filesystems
which I've never seen elsewhere.  The user found that version 3.1.2.2
is the most recent which works for him in that peculiar setting.  If
you can install 3.1.2.2 to see if it helps I'd be interested to know,
but it might be better for you to install the latest rsync-bpc from a
tarball that I can send to you - I'd be very keen to know how you get
on with it.  Alternatively, if you're up for it I can let you have a
debug version of 3.1.3 (or any other version) which will log a lot of
information on resource usage.  That might shed more light directly on
your issue.  Finally if you'd like to try the latest rsync-3.4.1rc1 I
can let you have the tarball.  I did deal with some memory issues when
I was working on it, but it's had little testing other than my use of
it for my own systems for a few months.  The version currently running
here was compiled on May 30th.  Building from source should be easy, a
couple of config tweakes might be needed.

Hosts appears to be backed up correctly in the UI, but when I look at the
XferLOG or browse the list of files from the UI, I see errors and missing
files/dirs.

It's disconcerting that you're seeing nothing in the UI to indicate
that there are problems with the backups - are you looking at the full
UI pages?  One or two of them are rather long, and the existence of
Xfer errors might not be obvious until you scroll a way down the page.
Do you have emailed alerts set up?  For your own peace of mind you
might want to set up something on the crontab to scan recent XferLOGs
for error messages nightly but this should all ideally be taken care
of by BackupPC itself of course.

I have observed two cases of corruptions so far.
One occurred during a network outage (at the beginning of the month) that
left some files unreadable as seen with `BackupPC_tarCreate` with errors
like `Unable to open file

The messages "Unable to open file ..." and "Error: padding ..."  are
expected if BackupPC_tarCreate runs into problems with its input data.

...
The second one occurred this evening, without any network outage, with a
host showing many errors in the XferLOG like:
- `G bpc_path_create: can't create f%2f/fetc (errno 2)`
- `rsync_bpc: recv_generator: mkdir "/etc/NetworkManager" failed: No such
file or directory (2)`
- `G bpc_poolWrite_updateMatches: can't open candidate file
/var/lib/backuppc/cpool/7c/1a/7d1acb7c259e7575f6d5f609c092cb8101 for read`
- `G bpc_attribCache_dirWrite: failed to write attributes for dir
f%2f/fusr/flib/fmodules/f5.15.0-156-generic/fkernel/fdrivers/fmedia/fplatform/fcadence/attrib
`

`/var/log/kern.log` shows a segfault at 06:00:

When I'm testing new code I see similar errors if rsync-bpc segfaults,
but it's not normally supposed to do that. :(  IIRC the user that I
mentioned earlier sees instead that the problem rsync-bpc processes
get killed by the OOM killer.  It might be worth looking at 'top'
while backups are running to see what's going on.  On my backup
servers I routinely log the output of 'top -b -n1' to a file every
five minutes as a way of keeping an eye on memory consumption, rsync
can somethimes get a little heavy.  You could try tweaking the kernel
memory management, e.g. /proc/sys/vm/overcommit_memory = 0 which will
would give you a hard memory allocation failure instead of some weird
error if things get out of hand with memory.

...
What I also find strange, is that the XferLOG seems to be garbled with what
looks like multiples processes overwriting each other and truncated lines,

Just a shot in the dark: are you accidentally running more than one
BackupPC process or something like that?  Again, that shouldn't happen.

...
I'm pondering switching to "tar" XferMethod to see if it helps...
...

If you can do that it would be very interesting to know what happens -
will you be using remotely mounted filesystems?

--

73,
Ged.


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