I love BackupPC it’s a truly awesome piece of software and a shining light in the open source world, but it can be cryptic and when it goes wrong the potential fallout is pretty major. The other day on one of my primary systems the backups began to fail with Fatal error during xfer (Child exited prematurely) no more detail simply that. This is precisely the sort of backup fail I dread, they always seem to become apparent just before bed time!
Anyway I needed to see the behind the scenes output of what Rsync was doing so instep the handy debug tool BackupPC_dump this is precisely the tool you need to debug “Fatal error during xfer” errors.
You can see the full instruction here but the key bit is:
The BackupPC_dump command has a -v option, so the easiest way to debug backup problems on a specific host is to run BackupPC_dump manually as the BackupPC user:
__INSTALLDIR__/bin/BackupPC_dump -v -f hostName
which for me translated to: