Re: [lvs-users] "IPVS: ip_vs_send_async error" flood

To: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] "IPVS: ip_vs_send_async error" flood
From: Siim Põder <siim@xxxxxxxxxxxxxxx>
Date: Wed, 12 May 2010 11:53:58 +0300
Tomasz Chmielewski wrote:
> I have "IPVS: ip_vs_send_async error" literally flooding in dmesg.

This usually happens when there are too many connection updates to
send in the default time (was around half a second IIRC) and they
don't fit in the send buffer.

That's probably not the case right now though.

> I had it in the past, but somehow solved it with this in sysctl.conf:
> net.core.wmem_max = 16777216
> net.core.rmem_max = 16777216
> Now it happens again, with barely no traffic (40 connections in DR mode 
> or so).
> What should I do to fix it?

Can you check with tcpdump if there are connection sync packets being
sent on the wire and how often/how long they are (host and
udp port 8848)?

Run netstat -npua (or similar) to see if there are listening sockets
on or any sockets that connect to

If there is a missing socket and no packets, perhaps something
happened with the sending socket and it got closed (would it close if
it got ICMP unreachable in response)? There does not seem to be any
more error handling than this message - so if the socket indeed got
closed (somehow) then it would never be detected and repaired and you
would just get one of these message at each sync sending attempt.


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