[Pacemaker] ifstatus OCF RA

[Florian Haas]

On 2011-02-22 00:19, Frederik Schüler wrote:
> Hi,
> 
> On Monday 21 February 2011 21:29:19 Florian Haas wrote:
>>> as the various ocf:*:ping[d] incarnations don't meet my specific needs,
>>
>> May I ask why and how?
> 
> ocf:pacemaker:ping works, but takes approx. 25-30s to react at all, and 
> approx. 40s to complete the failover. But I need an immediate failover, 
> exactly as it worked ages ago with heartbeat-2 and ipfail.

Well how about pushing down your monitor interval to something like 5
seconds, set attempts to 1, set timeout to 1, and dampen to 0? Then
basically as soon as you lose one ping, you can fail over.

>> Well, what if the link is up but there's an upstream problem?
> 
> Good point, but this requirement is customer-driven. I have the cluster to 
> initiate a failover as quickly as possible within the test cases.

This sounds like a good time to educate the customer that too short
failover times are more of a curse rather than a blessing. :)

> I have a working setup with ocf:pacemaker:ping, but this was rejected as being 
> "too slow".
> 
>> I've
>> always liked how ocf:pacemaker:ping actually monitors connectivity to an
>> upstream IP, which covers both immediate link failure and upstream
>> problems. Similar to how in active/backup bonding, you can fail over
>> based on the status of an ARP request, rather than MII link status.
> 
> I just checked the redhat cluster suite: the ip.sh RA there has a monitor_link 
> option, which does exactly what my ifstatus RA does. 
> Maybe this functionality could be added to the IPaddr2 script, but I guess 
> that wouldn't have more chances of being added than this one, correct?

Improving an existing resource agent pretty much always stands better
chances of being merged than adding a new one. That's my opinion, surely
others will correct me if theirs differ.

Cheers,
Florian

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