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I have a direct connection setup between my NAS and server with two gigabit links bonded in mode 0. I also have a single gigabit link from my server to my network. I want to test how the bond is performing in mode 0.

netstat -s | grep 'segments retransmited' | awk '{print $1}' -> 21983

netstat -s | grep 'segments send out' | awk '{print $1}' -> 91874454

21983/91874454 = .000239272

Is this considered high? There is a lot of traffic between this server and the internet.

Also, is there a better way to test packet loss on just the direct connection between my NAS and server? ethtool stats are not available because the driver is not supported. Thanks.

Alec Fenichel
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  • 0.02% packet loss is fine and not worth worrying about unless you deal with extremely critical transactions. You can use `iperf` to directly measure loss, bandwidth and jitter. – Mark Riddell Oct 01 '16 at 07:39
  • nstat can also help convert counters to rates https://loicpefferkorn.net/2016/03/linux-network-metrics-why-you-should-use-nstat-instead-of-netstat/ – Greg Bray Aug 13 '20 at 01:17

1 Answers1

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What is determined as "high" depends greatly on the application. In this case it's a fileserver using NFS, which is very forgiving to retransmissions.

In general if less than 1% of your traffic is redundant, you're in really good shape. You're far below that, so it doesn't look like this round-robin bond is causing retransmission issues (likely due to the fact that this is only a point-to-point link - a good use case for a mode 0 bond).

If you're having transmission problems regarding speed, you might look closer at jitter. This can be measured between two nodes that have iperf installed - not sure what your NAS is, though. balance-rr can cause issues with jitter, but in point-to-point links it shouldn't be a huge problem with NFS.

Spooler
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  • Thank you for the information. The NAS is a Synology Disk Station, not sure if it has iperf but I imagine I can install it. The speeds of file transfers are very inconsistent if I look at the NASs network statistics. Overall they average noticeably faster than gigabit so inconsistent but still fast. I wasn't sure if it was a network issue or some other bottleneck. Might even be the NASs network statistics, it sometimes says over 250MB/s which shouldn't be possible. – Alec Fenichel Oct 01 '16 at 14:44
  • How do you know that NFS is used here? – hertitu Oct 01 '16 at 20:40
  • It's not stated here, but the poster had asked in a different question about this very NFS server and the possible impacts of utilizing balance-rr for a single point-to-point link to a client machine for backups. It's only by happenstance that I know this is an NFS server. – Spooler Oct 02 '16 at 13:51