On Thu, Apr 17, 2014 at 4:59 PM, Michał Purzyński <
[email protected]> wrote:

> Hello.
>
> I'm trying to write to disk between 3-7Gbit/sec (traffic changes a lot).
> Netsniff-ng is dropping packets, at least that is what statistics say.
>
> Hardware and software details:
>
> 2 x E5-2620
> 64GB memory in 8 x 8 DIMMs to use every channel
> Intel X520 based card
> 12 x 3TB (2.7TB in fact) in RAID5 - 1 as hot spare, the rest gives me a
> healthy 28TB usable
>
> Ubuntu 12.04 on 3.8.x kernel
> XFS
>
> I run the software like this
>
> netsniff-ng -i eth2 -o /nsm/sensor_data/nsm2-eth2/dailylogs/2014-04-17/
> --user 2551 --group 2551 -s --prefix snort.log. --verbose --ring-size 4000
> iB --interval 1500 MiB --mmap --filter /etc/nsm/nsm2-eth2/bpf-pcap.ops
>
> BTW - there is a bug (integer overflow) and the buffer can't be larger
> than 4095MB. Anyway.
>

My understanding is that it's not really a bug but due to the nature of
mmap(),
I have an issue created for that if something can be done about it. [1]


> What can I do to make netsniff lossless in this situation? Can it even do
> it?
>

You may attempt to try the suggestions in the following thread that speak of
page/flush tuning and load balancing [2]. Mapping, say 64GB of RAM to a
tmpfs mount point
and writing to it may be worth a try as it may hint to the bottleneck (disk
gets the blame often).


> Also, I've disabled every kind of offloading feature I could find, and
> build the new Intel drivers with LRO=0.
>

[1] https://github.com/netsniff-ng/netsniff-ng/issues/90
[2] https://groups.google.com/forum/#!msg/netsniff-ng/vPeYPZzh1Es

Thanks
-- 
Jon Schipp,
jonschipp.com, sickbits.net

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