Q:

MySQL - Master/Slave Replication with different server specs

I have a Master/Slave replication (using MySql 5.1 / InnoDB).
Currently both my master & slave are running on the same type of server (32 GB RAM, 2 x Intel Xeon 5520 Quad Core 2.26 GHz (8 cores)) and have the same type of configuration (in terms of innodb_pool_size etc.)
I am considering upgrading my master to a stronger machine (48GB RAM, 2 x Intel Xeon 5640 Six Core 2.26 GHz (12 cores)).
My question is: Is it possible to upgrade just the master (increase his buffer_bool_size etc.) and leave the slave at his current setup?

A:

Yes you can upgrade the Master's my.cnf file to handle the new environment.
I have an additional suggestion.
InnoDB prior to MySQL 5.1.38 cannot use multiple CPUs.
You can do one of two things that will not affect the Slave

Upgrade to Percona Server 5.1
MySQL 5.1.38 has InnoDB Plugin (dsiabled by default) which acceses mulitple CPUs

If you have MySQL 5.1.37 or prior, upgrade to the latest MySQL 5.1 and install InnoDB Plugin
If you have MySQL 5.1.38+, install InnoDB Plugin

Once you do, one of the above, you can configure the necessary options for accessing multiple CPUs

About single threaded versus multithreaded databases performance
Possible to make MySQL use more than one core?

