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Re: [Linux-cluster] CCSD ipv6 bind failures



hi Fabio,
            Thanks for your replies.

> "Unable to bind to backend ipv6 socket, but inet_ntop returned NULL
> pointer: Address already in use"
This issue is not seen always. We see this problem when our application is run for the first time after it is installed. cman start fails as a result of these logs since ccsd fails and it keeps retrying. Rebooting the node helped us get rid of the logs.
Its possible that ipv6 module did not load when binding was attempted. But if you look at the log, it says binding failed for "backend" port (50007). Under normal running of system, netstat does not list this port number against ccsd. Instead frontend (50006) and cluster_base_port (50008) are listed. Any idea why backend port binding is attempted and that too only when our application is freshly installed and run?

Regards,
Ashish

On Tue, Dec 18, 2012 at 12:47 PM, Fabio M. Di Nitto <fdinitto redhat com> wrote:
On 12/5/2012 2:52 PM, Ashish G wrote:
> hi Experts,
>                I has few question on ccsd:
> 1. what is the purpose of ccsd listening on ipv4 and ipv6 addresses as
> follows in my 2 node HA setup? We do not use IPv6 in our setup.
>
> netstat -antp |grep ccsd
>
> tcp        0      0 0.0.0.0:50008 <http://0.0.0.0:50008>
> 0.0.0.0:*                   LISTEN      18170/ccsd
>
> *tcp        0      0 ::1:50006
> :::*                        LISTEN      18170/ccsd*
>
>
> **
>
> *CCSD is invoked without any arguments:
> *
>
> *root     18170     1  0 14:12 ?        00:00:00 /sbin/ccsd*
>

RFCs now mandates software to support both IPv6 and IPv4 and v6 has to
be preferred when available.

>
> 2. Is it not sufficient to use IPv4 only by CCSD?

For operational purposes yes, one protocol is enough, but we need to
support both.

>
> 3. Sometimes on node reboot we see messages as follows:
>
> "Unable to bind to backend ipv6 socket, but inet_ntop returned NULL
> pointer: Address already in use"
>
> Does anyone know when is this problem seen?

No, it´s probably harmless. Does it create any runtime problem? I guess
that the kernel ipv6 module is not loaded and bind fails.

>
> 4. If I invoke CCSD with "-4" option, will I get rid of the above
> message? since ipv6 code path will not hit.
>
> *root       461     1  0 14:28 ?        00:00:00 /sbin/ccsd -4*
>
> netstat -antp  |grep ccsd
>
> *tcp        0      0 127.0.0.1:50006 <http://127.0.0.1:50006>
>     0.0.0.0:*                   LISTEN      461/ccsd*
>
> tcp        0      0 0.0.0.0:50008 <http://0.0.0.0:50008>
> 0.0.0.0:*                   LISTEN      461/ccsd
>

Just try it, if you are not using v6, specifying -4 should be enough.

Fabio

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