On Wed, Jan 7, 2009 at 12:56 PM, William McKee <william AT knowmad DOT com> wrote:

Hi all,

This evening I tracked down a configuration error that was causing a
bandwidth spike due to a misconfiguration of BackupPC (v2.1.2). I set
the IncrPeriod to 0.00 thinking that no incrementals would get run. Boy
was that wrong! Instead, it ran incrementals one after another during
off-peak hours. That spiked my bandwidth with my hosting provider which
sent me searching for the culprit.

Because of the holidays, I had forgotten about the edit of the
IncrPeriod so wasn't sure what was causing the spike. Thus I went
digging through my logs and such to try to identify the culprit.

I use VMware on a co-lo server which has 3 guestts that all get backed
up by BackupPC. I could identify that the host was transmitting massive
amounts of data (130Gb) which appeared to be coming from one of the
three guests. However, I couldn't figure out which guest was pushing out
the excessive data.

I went through the usual log files without much luck. I then checked the
ifconfig output which all looked normal inside the hosts. Once I finally
looked at the BackupPC logs for the guest server, I realized what was
happening and corrected the issue by removing my bad entry. I also added
--bwlimit to the RsyncArgs setting in config.pl to control maxing out my
bandwidth.

However, this all took longer than I'd have liked. I'm stumped as to why
the data transmitted off of the guest did not show up in the ifconfig
output. I know that the guest is sending data via rsync based on the
logs. However it's not showing up in the ifconfig stats (see below). Is
this due to the way that rsync works? I was sending about 450Mb of data
every 1-2 hrs from 8pm - 6am (I can send the logs if that would be of
any help). I've included below the ifconfig outputs for the host
(massive TX bytes) and the guest (normal TX bytes). I would have
expected a corresponding amount of TX bytes for the guest. Thanks for
any insight.


Cheers,
William



Output of ifconfig on host (atlas)
eth0      Link encap:Ethernet  HWaddr 00:17:A4:3F:C3:B5
         inet addr:64.132.42.194  Bcast:64.132.42.207  Mask:255.255.255.240
         inet6 addr: fe80::217:a4ff:fe3f:c3b5/64 Scope:Link
         UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
         RX packets:67509721 errors:0 dropped:0 overruns:0 frame:3
         TX packets:102403892 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1000
         RX bytes:6915124969 (6.4 GiB)  TX bytes:139582421865 (129.9 GiB)
         Interrupt:16


Output of ifconfig on guest (wg75)
eth0      Link encap:Ethernet  HWaddr 00:0c:29:2a:5f:cd
         inet addr:192.168.233.25  Bcast:192.168.233.255  Mask:255.255.255.0
         inet6 addr: fe80::20c:29ff:fe2a:5fcd/64 Scope:Link
         UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
         RX packets:26307738 errors:0 dropped:0 overruns:0 frame:0
         TX packets:42720081 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1000
         RX bytes:2111065627 (1.9 GB)  TX bytes:2438535854 (2.2 GB)
         Interrupt:17 Base address:0x1400


--
Knowmad Technologies - Open Source Web Solutions
W: http://www.knowmad.com | E: william AT knowmad DOT com | P: 704.343.9330

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