[Spread-users] migrating from spread-3.17 to spread-4.0...questions
John Lane Schultz
jschultz at spreadconcepts.com
Thu Jan 4 13:59:30 EST 2007
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.
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!
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