maria-developers team mailing list archive

[erkan yanar <erkan.yanar@xxxxxxxxxxxxx>]

Ahoi Pavel,
On Fri, Nov 15, 2013 at 01:59:49PM -0800, Pavel Ivanov wrote:
[snip]
> > As an example here's an independent comparison of Galera vs.
> > semi-sync performance:
> > http://linsenraum.de/erkules/2011/06/momentum-galera.html.
> 
> This is a nice blog post written in German and posted in 2011. And
> while Google Translate gave me an idea what post was about it would be
> nice to see something more recent and with better description of what
> was the actual testing set up.

it is my post and as a fact you are right a newer one would be also nice.
As a fact there is one: http://linsenraum.de/erkules/2012/03/galera-als-replikationsersatz.html
(Even there is a mistake: missing setting for innodb_flush_log_at_trx_commit=0). There you also 
get some infos about the used hardware
I think Im going to write a new one. Also with newer hardware. And there will be an English version.

The basic idea oft the tests is. Not to rely on the 'master'. Thats why I used settings like
innodb_flush_log_at_trx_commit=0 and innodb_doublewrite=0
The basic idea is not to rely on any data of a crushed node.
Working also in 'cloudenvironments' I prefer to rebuild instead to repair a node.

To make it short. 

* Galera is always faster than Semisync. You can compare it to async repl. 
  It gets his speed out of the parallel applying.

* With Galera you have (virtual) synchronous replication. 
  Using Semisync you know nothing. All you can do is monitoring semisync variables.
  But I doubt it will tell you anything about the 'last' transactions

So you got async repl speed with synchronous data \o/


Regards
Erkan


-- 
über den grenzen muß die freiheit wohl wolkenlos sein