[Linux-cluster] CCSD ipv6 bind failures

[Fabio M. Di Nitto]

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