[Spread-users] migrating from spread-3.17 to spread-4.0...questions

[John Lane Schultz]

Hi John,

Spread 4 breaks protocol compatibility with Spread 3.  If you brought up a 
Spread 4 daemon in a Spread 3 ring, then the Spread 4 daemon would completely 
ignore the Spread 3 daemons and eventually form its own singleton "ring" due to 
new functionality in Spread 4.

However, I'm not 100% sure what the Spread 3 daemons would do.  Hopefully, they 
would perceive the Spread 4 daemon's traffic as malformed and also ignore it. 
Failing that, they might perceive it as a daemon and begin trying to form a ring 
with it.  Of course, the Spread 4 daemon would ignore that attempt and the 
attempt would eventually fail.  All of that should leave the Spread 3 ring 
running without interruption but there would be more generated traffic as they 
persistently try (and fail) to form a new ring with the Spread 4 daemon.

I do not know if mod_log_spread and spreadlogd have been ported to Spread 4 as 
of yet.  If not, it wouldn't take much work as the Spread 4 client interface is 
very similar to Spread 3's.

Cheers!
John

john allspaw wrote:
> Hey all - 
> 
> I've got about 100 apache boxes speaking error/access logs in 10 different rings, with mod_log_spread doin
> the talking to a spreadlogd daemon on a single machine.
> 
> We've seen some situations where UDP storms will happen from time to time, and I think I'd like to 
> get spread-4.0 running, since the changelog looks like it's got some good stability fixes.
> 
> Question is: in order to test spread-4, is there any reason why I can't deploy spread-4 onto *one* of the nodes, even if the rest
> of them in the ring are spread-3.17 ?  or do I have to deploy the whole ring with spread-4 ?
> and...since the log aggregation machine is essentially listening on all rings, should I also upgrade
> the spread daemon on the spreadlogd host ?
> 
> thanks in advance!
> John 
> 

-- 
John Schultz
Spread Concepts LLC
Phn: 443 838 2200
Fax: 301 560 8875