[rt-users] Splitting queries across mysql servers

[Parish, Brent]

I'm running one instance, which is on a Sun v240 (4gb RAM, 2x1GHz CPU),
which also runs the database.  The second server is a complete mirror of
the first, both in hardware and software.  
$DatabaseHost is set to the MySQL virtual IP that I would swing back and
forth between servers as needed.  The RT web interface (apache) is also
tied to a virtual IP, so that would swing over as well.
In the my.cnf, set the replicion values to something like this:
auto_increment_increment = 2
"auto_increment_offset = 2" on one server, and "= 1" on the other (to
make one auto increment using even numbers, the other odds)
master-host = (set this to the IP of the private interface/crossover
cable to the second server, so it uses the gigE, not the default network
interface) 

Brent


-----Original Message-----
From: Roy El-Hames [mailto:rfh at pipex.net] 
Sent: Thursday, September 07, 2006 5:03 AM
To: Parish, Brent
Cc: Drew Taylor; rt-users at lists.bestpractical.com
Subject: Re: [rt-users] Splitting queries across mysql servers

This sounds good
How many web interfaces (rt instances) are you running, how did you set 
up $DatabaseHost in the RT config??
Roy
 

Parish, Brent wrote:
> I'm using circular replication in MySQL and LOVE it!
> The idea is that each MySQL host points at the other as a slave, so
all
> updates go to both hosts.  The problem with that in the past is that
> tables using auto-increment columns could get whacked if both servers
> added a row at the exact same time and contended for that next
> incremented value.  
> MySQL now has values you can set in my.cnf that tell one server to use
> odd numbers (e.g.) and the other evens.
> Works like a charm, though there is no automatic failover.  I run the
DB
> attached to the base IP for the server, as well as a virtual IP that
can
> swing over (by hand) to the other.  Lastly, they share a crossover
cable
> (direct cable) interface to do the replication over GigE.
> You can check out the Heartbeat project for IP failover, but I've not
> had time to dig deep into that yet (one dragon to slay at a time,
> please!).
> HTH
> - Brent Parish
>
>
>
>
> -----Original Message-----
> From: rt-users-bounces at lists.bestpractical.com
> [mailto:rt-users-bounces at lists.bestpractical.com] On Behalf Of Drew
> Taylor
> Sent: Tuesday, September 05, 2006 5:24 PM
> To: rt-users at lists.bestpractical.com
> Subject: [rt-users] Splitting queries across mysql servers
>
> Hi,
> (Now subscribed from my personal address)
>
> We're looking to scale our RT instance at $work, and make it more
fault
> tolerant at the same time. The obvious first step is to split the DB
out
> from the Mason servers (currently all on one box). At the same time,
we
> want to use mysql replication to get the data onto a second DB server.
> In a perfect world we would have RT transparently be able to do
SELECTs
> on both DB boxes while sending UPDATE/INSERT statements to the master
> DB.
>
> I know I'm not the first person to attempt this. :-) Any pointers to
DBI
> multiplexers, tips, etc would be most appreciated.
>
> Thanks,
> Drew
> --
> ----------------------------------------------------------------
>  Drew Taylor                 *  Web development & consulting
>  Email: drew at drewtaylor.com  *  Site implementation & hosting
>  Web  : www.drewtaylor.com   *  perl/mod_perl/DBI/mysql/postgres
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