MySQL - Master/Slave Replication with different server specs

Question

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?

• Derek Downey: Just curious, what type of load does your slave handle. Is it just a load-balanced read server, or does it even handle traffic at all?

Answer 1

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?

• Ran: by running SELECT version(); i know that im running 5.1.61-0ubuntu0.11.10.1-log. do I still need to upgrade / install the InnoDB plugin? or am I good to go?
• RolandoMySQLDBA: Since you are using MySQL 5.1.61, you should install the InnoDB Plugin for InnoDB. Make sure it is there by running this Query : SELECT * FROM mysql.plugin;.
• Ran: Are there any other, positive / negative replications for installing the plugin? Any good tutorial for installing the plugin?

Answer 2

As long as your individual servers' settings don't exceed the capacity of the server (for things like memory usage), there is no problem with running different server specs. What I mean is that you don't copy the master's new configuration settings that utilize the 48GB RAM to the slave.

Answer 3

If you are maxing out the Master, guess what will happen in the Slave? It will get behinder and behinder. That is, you may need the Slave to be at least as powerful as the Master.

• konung: Depends on what his slave is used for. In my case my slave is a very under-powered VM, that is only used for backups ( mysql dumps) and some long running background reports. Actual replication is not that resource intensive.
• Wouter: How did you decide on the specs for the underpowered VM? Is there a factor for CPU and RAM that you used (like 1/4 of master) or what specifically?