[PATCH v2 0/6] Add fence kdump support

[Marek Grac]

On 01/24/2014 03:48 PM, Vivek Goyal wrote:
> But dump time varies based on machine type. So if you add a machine
> to cluster with large amount of memory, it could take 30minutes easily
> to dump.
>
> And there is no documentation which explains how much time it will take
> to dump. Nobody knows.
Yes, that's true.

> I am sorry I still don't understand how does this timeout logic work.
>
> - Is it a tick based mechanism where 60 seconds represent the interval
>    in which atleast one tick should be received.
>
> - Or is it absolute upper limit of time in which dump should be completed.
Problem is that I did not describe it precisely enough, so don't worry. 
There are two timeouts:
* fence_kdump
     - tick based mechanism, 60 seconds for valid message, upper bound 
is infiity
     - usable everywhere even without cluster

* using fence_kdump with pacemaker/corosync cluster
     - the most usual combination
     - cluster has it's upper limit in which fencing has to be finished 
otherwise it is considered to be failed
     - this timeout has to be set to a value which is system-dependant
     - fencing will fail if previous timeout is not enough and if no 
message was received in 60 seconds (fence_kdump fails -> fencing fails)

m,