[ClusterLabs] Corosync 3.1.0 token timeout

[Ulrich Windl]

>>> Jan Friesse <jfriesse at redhat.com> schrieb am 20.10.2020 um 18:05 in Nachricht
<9e9edd13-847c-a81f-9b28-0ecf8f17fd48 at redhat.com>:
> I've forgot to mention one very important change (in text, release notes 
> at github release is already fixed):
> 
...
> 
> - Default token timeout was changed from 1 seconds to 3 seconds. Default 

Hi!

The same stupid question as always: How is that value determined, assuming that in a LAN the per-hop delay should be less than 1ms these days and the numbe rof nodes typically is much less than 10. Ist there a safety-factor of 1000%, or what?
Or is this just black magic, and the value was determined in a sleepless fulll-mood night by throwing dice?

Regards,
Ulrich

> token timeout of 1000 ms was often changed by users because of other 
> workloads on machine which may make corosync responding a bit later than 
> needed and resulting in token loss. 3000 ms was chosen as a compromise 
> between token timeout increase and allow live cluster upgrade (other 
> nodes should receive token by node with new default on time). It doesn't 
> affect token token_coefficient so final token timeout still depends on 
> number of configured nodes (just base is higher).  This change slows 
> down failover a bit so for clusters where failover times are important, 
> please change the token timeout in configuration file corosync.conf as a:
> 
> totem {
>    version: 2
>    token: 1000
>    ...