dovecot - Mar 2009 - multiple sql servers - loadbalancing and failover

Hi,

Is there a way for dovecot to use a pool of sql (mysql) servers and load 
balance queries between these?

Also fallback to next available sql server if connection to previous one 
fails.

Can dovecot do such things currently? (If not this is feature request).

-- 
Arkadiusz Mi?kiewicz        PLD/Linux Team
arekm / maven.pl            http://ftp.pld-linux.org/

You can try mysql-proxy:

http://dev.mysql.com/downloads/mysql-proxy/index.html



On Fri, 27 Mar 2009 11:20:37 +0100 Arkadiusz Miskiewicz <arekm at
maven.pl> wrote:
> 
> Hi,
> 
> Is there a way for dovecot to use a pool of sql (mysql) servers and load 
> balance queries between these?
> 
> Also fallback to next available sql server if connection to previous one 
> fails.
> 
> Can dovecot do such things currently? (If not this is feature request).
> 
> -- 
> Arkadiusz Mi?kiewicz        PLD/Linux Team
> arekm / maven.pl            http://ftp.pld-linux.org/
> 
> 
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> 
> The message was checked by ESET NOD32 Antivirus.
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> 
> 

--
Xueron Nee
http://www.xueron.com

On Friday 27 of March 2009, Xueron Nee wrote:
> You can try mysql-proxy:
>
> http://dev.mysql.com/downloads/mysql-proxy/index.html
This introduces single point of failure.

Support for switching to next mysql server in list if previous fails would be 
enough. 
-- 
Arkadiusz Mi?kiewicz        PLD/Linux Team
arekm / maven.pl            http://ftp.pld-linux.org/

Arkadiusz Miskiewicz wrote:
> On Friday 27 of March 2009, Xueron Nee wrote:
>> You can try mysql-proxy:
>>
>> http://dev.mysql.com/downloads/mysql-proxy/index.html
> 
> This introduces single point of failure.
> 
http://forge.mysql.com/wiki/MySQL_Proxy#Load_Balancing_.26_Failover

Arkadiusz Miskiewicz wrote:
> On Friday 27 of March 2009, Xueron Nee wrote:
>> You can try mysql-proxy:
>>
>> http://dev.mysql.com/downloads/mysql-proxy/index.html
> 
> This introduces single point of failure.
> 
Plus use of heartbeat, HA, etc.

On Friday 27 of March 2009, Seth Mattinen wrote:
> Arkadiusz Miskiewicz wrote:
> > On Friday 27 of March 2009, Xueron Nee wrote:
> >> You can try mysql-proxy:
> >>
> >> http://dev.mysql.com/downloads/mysql-proxy/index.html
> >
> > This introduces single point of failure.
>
> http://forge.mysql.com/wiki/MySQL_Proxy#Load_Balancing_.26_Failover
If I get this right if mysql proxy fails I still get nothing. Hm, I would have 
to run mysql proxy on every machine that has dovecot installed. Then it would 
make some sense.

Ok, that should work.
-- 
Arkadiusz Mi?kiewicz        PLD/Linux Team
arekm / maven.pl            http://ftp.pld-linux.org/

On Friday 27 of March 2009, Seth Mattinen wrote:
> Arkadiusz Miskiewicz wrote:
> > On Friday 27 of March 2009, Xueron Nee wrote:
> >> You can try mysql-proxy:
> >>
> >> http://dev.mysql.com/downloads/mysql-proxy/index.html
> >
> > This introduces single point of failure.
>
> Plus use of heartbeat, HA, etc.
This makes thing much more complicated  than it can be especially in setup 
like mine where servers are not only doing mysql serving but another thasks 
and the "failure" can be so simple like "service mysql
stop".

-- 
Arkadiusz Mi?kiewicz        PLD/Linux Team
arekm / maven.pl            http://ftp.pld-linux.org/

On Mar 27, 2009, at 3:20 AM, Arkadiusz Miskiewicz wrote:
> Is there a way for dovecot to use a pool of sql (mysql) servers and  
> load
> balance queries between these?
>
> Also fallback to next available sql server if connection to previous  
> one
> fails.
>
> Can dovecot do such things currently? (If not this is feature  
> request).
Yes, it can! Just add more multiple host= parameters to connect  
string. It's actually even documented in the dovecot-sql-example.conf:

#   MySQL supports multiple host parameters for load balancing / HA.

I guess it's not mentioned in the wiki though.