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Lets forget about 'multi'-master scenario. It is basically an unsolvable
problem for MySQL (at the moment).
The only sensible muti-server setup for MySQL is 'single master' -
'mutiple slave', preferbly in 'star shape formation' i.e. each slave
connected directly to master. Also don't bother about 'dasiy-chaining'
the slaves, this creates a single point of failure (those were the days
of token ring networks) ;)
Jan Klopper wrote:
True,
But as soon as you start doing updates to the database you will
horribly screw up your data, because mysql can't propogate the changes
made on slaves back tot the master and so on.
This will lead to loads of inconsistency's in you database.
If you only need to do load (and i mean loads) of select query's with
no changes than you could very well use mysql slaves inside a LVS to
run these query's.
Even normal master-slave replication still gives loads of problems, so
anything cutting edge which might do the trich and allow for the
slaves to be full database servers (and thus capable of handling
updates/inserts/deletes) should not be trusted in my opinion.
Granted, if they get the slaves to also be masters to each other, and
they get it to pay nice, then we're all set to have the best and
fastests clustering database on the planet (except for oracle?), Maybe
it would be nice to get some people to take a look at this?
Im considering the use of a filesystem like coda to do two way file
replications, but maybe storing a filesystem inside a clustering and
two way updating mysql system is much better.
Francois JEANMOUGIN wrote:
Jan Klopper :
Sent: Wednesday, March 02, 2005 9:48 AM
To: aero_climb@xxxxxxxx; lvs-users@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re: Mon + LVS for a mysql cluster
Romain,
There is not good sollution for mysql and clustering.
Tup tup tup. That's what is called an assertion, man :).
The current state of the artr for MySQL is to use an NBD cluster. You
can use
LVS to load-balance connections to your MySQL servers. You need a small
management server to manage it.
Now, to check whether a MySQL server is available or not, you have two
solutions (assuming you choose Keepalived):
Use a TCP_CHECK that will detect if the server accepts connections.
Use the check_mysql from nagios-plugins embedded in a MISC_CHECK script.
Probably you can do more complicated things with THC but, I didn't
find time
yet to test it, so, I can't help.
François (et hop).
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