I'm inspecting a problem with a MongoDB replica set reelecting a primary multiple times per minute. It seems that there is something wrong with the network configuration, but I can't nail it down yet.

When running ifconfig on the virtual machine of one of the nodes, I see a high number of TX collisions on eth0:

RX packets 850479  bytes 253445128 (241.7 MiB)
RX errors 0  dropped 12070  overruns 0  frame 0
TX packets 512851  bytes 210486965 (200.7 MiB)
TX errors 0  dropped 0 overruns 0  carrier 0  collisions 2648104

I don't understand what it means.

When I search what exactly are TX collisions, all I find is that those are related to the actual, physical network cables. However, the hardware server hosting this virtual machine reports zero collisions.

So what exactly is a TX collision in a context of a virtual machine (a Debian 9 running on QEMU/KVM, hosted on Ubuntu 18, if it matters)?

  • could it be the same issue? lists.debian.org/debian-user/2017/07/msg00348.html (even if there has to be a bug somewhere, if changing to a VM-optimized virtual card helps...) – A.B Nov 9 '19 at 19:55
  • @A.B: it could be, indeed, since I'm using rtl8139 instead. Unfortunately, virtio doesn't work (the VM has no network connection if virtio is specified), and I never took the time to check why; seems like a good opportunity to finally check it. – Arseni Mourzenko Nov 10 '19 at 9:59

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