[ClusterLabs] Corosync 2 vs Corosync 3

[Jan Friesse]

On 25/10/2021 16:42, Ken Gaillot wrote:
> On Mon, 2021-10-25 at 13:44 +0000, Toby Haynes wrote:
>> Looking at Pacemaker 2.1, I see that both corosync 2 and corosync 3
>> are supported. The last corosync 2 release (2.4.5) came out in 30
>> July 2019. Will there come a point when a future Pacemaker release
>> might only support the Corosync 3 (or later) series?
> 
> There's nothing that Pacemaker has to do specially for Corosync 2 vs 3,
> so it's unlikely support will ever be dropped for just 2. Of course
> everything changes eventually, but nothing's on the horizon.
> 
> If you're choosing between the two, keep in mind Corosync 3 doesn't
> support rolling upgrades from 2, even though Pacemaker itself doesn't
> care.
> 
>> Are there good use cases today where Corosync 2 is a better choice?
> 
> Not that I know of. I'd only use it when it's what the OS provides.
> There are a few features only supported by 2 (like node discovery via
> multicast), but I don't think they're worth staying on 2.


Just to add that Corosync 2 will probably get only one final release and 
we will stop supporting it completely, so I would recommend to choose 
Corosync 3 (with exception where your distro still ships Corosync 2 only 
- then it is probably better to use distro package).

Regards,
   Honza

> 
>> Thanks,
>>   
>> Toby Haynes