William,
Is the guest machine "multi homed" - with multiple network interface cards.
Linux binds a IP Address to "entire OS" rather than to a "specific
interface" unlike some of the other UNIX flavors that binds it only to the
interface. If it is really multi-homed, you might get a clue by looking at
the ifconfig output of all eth? interfaces. There might be another eth?
interface that would have a corresponding increase of packets that you are
expecting...
HTH
Vasan
On Wed, Jan 7, 2009 at 12:56 PM, William McKee <will...@knowmad.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: will...@knowmad.com | P: 704.343.9330
>
>
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