[Ocfs2-devel] [PATCH 3/3] o2net: correct keepalive message protocol

[Srinivas Eeda <srinivas.eeda@oracle.com>]

No harm, just doubles heartbeat messages which is not required at all.

Sunil Mushran wrote:
> What's the harm in leaving it in?
>
> Srinivas Eeda wrote:
>> Each node that has this patch would send a O2NET_MSG_KEEP_REQ_MAGIC 
>> every 2 seconds(default). So, nodes without this patch would always 
>> receive a heartbeat message every 2 seconds.
>>
>> Nodes without this patch will send(respond) with 
>> O2NET_MSG_KEEP_RESP_MAGIC for every keep alive packet they received. 
>> So nodes with this patch will always receive a response message.
>>
>> So, in a mixed setup, both nodes will always hear the heartbeat from 
>> each other :).
>>
>> thanks,
>> --Srini
>>
>>
>>
>> Joel Becker wrote:
>>  
>>> On Thu, Jan 28, 2010 at 08:51:11PM -0800, Srinivas Eeda wrote:
>>>      
>>>>          case O2NET_MSG_KEEP_REQ_MAGIC:
>>>> -            o2net_sendpage(sc, o2net_keep_resp,
>>>> -                       sizeof(*o2net_keep_resp));
>>>> +            /* Each node now sends keepalive message every
>>>> +             * keepalive time interval. Hence no need for response
>>>> +             */
>>>>              goto out;
>>>>           
>>>     You still have to send the response.  Think about a mixed
>>> environment where some nodes have this fix and some do not.  The older
>>> software is still waiting on the response.
>>>     The newer version can just ignore any responses it gets from
>>> other nodes.  But it has to send responses out just in case the other
>>> node is older.
>>>     The only other alternative is to bump the o2net protocol
>>> version, and that means the cluster has to be shut down to upgrade.  
>>> Not
>>> a good choice.
>>>
>>> Joel
>>>
>>>       
>>
>>
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>