Re: TCP failed connection attempts

[Sergey Malinin <hell@xxxxxxxxxxx>]

On 26.03.14, 17:48, Ирек Фасихов wrote:

Hi, Daniel.

I use the following settings:

net.ipv4.tcp_syncookies = 0

net.ipv4.tcp_moderate_rcvbuf=0

net.ipv4.tcp_low_latency = 1

Message "failed connection attempts", can be ignored, it is not just a server error, but the client. For example: A client lost its connection to the server.

It refers to connection attemtps, that means loss of established connection will not affect the counter.

2014-03-26 18:29 GMT+04:00 Dan Van Der Ster <daniel.vanderster@xxxxxxx>:

Hi all,

I recently noticed our OSD servers have a very large number of TCP failed connection attempts. This is typical (output from netstat -s):

    50329019 active connections openings

    15218590 passive connection openings

    44167087 failed connection attempts

Taking into account that presumably you don't have anything besides osd daemon running on the machine, i would say that this is extraordinarily large
number indicating that something is definitely going wrong.

I’m not a TCP expert at all — but this doesn’t look good. Do others have similar numbers? Does anyone know if some ipv4 sysctl tuning can clear this up?

'netstat -s' provides verbose display of /proc/net/snmp counters for your information. These counters don't need to be reset or cleared up in some other way.

Cheers, Dan

-- Dan van der Ster || Data & Storage Services || CERN IT Department --

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С уважением, Фасихов Ирек Нургаязович

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