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

[Sunil Mushran]

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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