On Wed, Jan 18, 2017 at 7:03 PM, John Spitzer <johned9999 AT comcast DOT net> 
wrote:
> After much debugging, using strace and looking at logs, I think I'm on a
> better track about what may be happening. I sincerely welcome it if anyone
> reading this has more inside info about how BackupPC might be contributing
> to this.

Is this backuppc v3 or v4?

> Based on the strace and logs, I've come to lean in the direction that rsync
> is very involved in this. The backup I'm creating has quite a few very large
> files. On the order of 20 - 50 GBytes in size. These are VirtualBox VMs disk
> files. The backup is being made to a NAS where the network share is mounted
> on the backuppc server.
>
> The indications from the rsync log is:
> --------
> 2017/01/17 21:34:34 [3936] connect from localhost (127.0.0.1)
> 2017/01/17 21:34:34 [3936] rsync on . from backuppc@localhost (127.0.0.1)
> 2017/01/17 21:34:34 [3936] building file list
> 2017/01/17 22:13:02 [3936] [sender] io timeout after 302 seconds -- exiting
> 2017/01/17 22:13:02 [3936] rsync error: timeout in data send/receive (code
> 30) at io.c(195) [sender=3.1.0]
> ----------

Are you using rsyncd at the other end or did you change the rsync
command to enable logging?   I didn't think rsync itself has a default
timeout anywhere but you can set one.

> As far as I can tell, BackupPC has at least two pipes open, a read pipe and
> write pipe , to the backup archive (plus other sockets, files, etc). It
> looks like the write pipe has timed out after about 300 seconds. This time
> is very consistent in multiple runs. This timeout occurs while the read pipe
> is executing MANY reads from the file being backed up. (I'm guessing to
> determine if the file in the backup is the same as the one being backed up.)
> Because the read is taking so long, the write pipe has no activity and is
> timing out.

Pipes do not have any timeout.

You mentioned that the backup is actually stored on a NAS device.   Is
this NFS mounted and running over the same network segment?

-- 
   Les Mikesell
      lesmikesell AT gmail DOT com

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