BackupPC incorrect 'no ping response' error message

I discovered a bug with BackupPC's error reporting.  This has hit me more than once (evidenced by the deja vu I experienced when debugging the problem), but I mustn't have written down the solution previously.  A quick Google (by which I mean "skimming the first two screens of hits") doesn't show any obvious signs of people having the same issue, so I thought I'd document it here for search engine posterity.

The basic issue is that backups to certain systems fail, and the diagnostics shown in the web interface look like this:

  • Last status is state "idle" (no ping) as of 11/2 14:00.
  • Last error is "no ping response".
  • Pings to laptop1 have failed 39 consecutive times.

However, no ping response is not the problem.  If I login as the backuppc user on my backup server, it is able to both ping and ssh to the host in question just fine.

Digging deeper in the logs, I found this in /var/lib/backupppc/log/LOG:

2012-11-02 14:52:05 laptop1: mkdir /var/lib/backuppc/trash: Permission denied at /usr/share/backuppc/lib/BackupPC/ line 629

I fixed this by chowning /var/lib/backuppc to the backuppc user, and the backup proceeded as normal.  So it seems that backuppc will not do the right thing without a trash directory in place, and if it doesn't have permissions to create it, it gives a misleading error message.

In my case, this happened because my removable drive for backups died and I replaced it with a new one without fully recreating the directory structure as required by backuppc.  So I guess it's my fault, but a more helpful error message would have been good.

Related posts