This is a continuation of the saga of helping a customer of ours with their MySQL on Windows issues.
The basic premise is that MySQL 5 running under Windows has problems with large numbers of connections/open files.
We initially presented our client with 2 choices for solving their problem:
- Setup MySQL on a different server running Linux
- Move their database backend from MySQL to Microsoft SQL Server
Option 1 would require a non-trivial capital outlay and time to setup and migrate the data over
Option 2 held more interest for them as a longer term solution as they were interested in some of the powerful reporting and analysis tools. However, the server that all of this was running on turned out to present a problem in the following way:
The system is a Dell PowerEdge 2950 with dual dual-core Xeons (with HyperThreading enabled, resulting in 8 logical cpus), 8GB RAM and running Windows 2003 Server x64. For a general ballpark estimate of pricing for MS SQL Server, I went to the Dell website and configured a similar machine and went to select a SQL Server as an add-on. Due to the way that Microsoft prices SQL Server for a web environment, you must license it for each processor you have installed in your server. A dual-processor licensed SQL Server 2005 running under Windows x64 turned out to be in excess of $14,000 on that page.
Needless to say, the customer had a bit of sticker shock. Not only would they have to plop down FOURTEEN grand, they would still need man-hours to work out kinks in transitioning the backend of the app from MySQL. Getting a fully loaded separate server for half that cost running Linux/MySQL was looking more attractive.
I was chatting with a friend about the customers dilemma and he had a brilliant suggestion: Run a Linux instance under VMWare on the existing hardware.
I broached the idea with the client and they were game to give it a shot. The server was at this point extremely underutilized and was only limited by the specific software implementations. They were already running MySQL here anyway, so putting a different wrapper around it in order to escape those limits was worth investigating.
The server needed some more disk space so they ordered 6 more of the 146GB 2.5″ SAS drive modules like the 2 that were already installed in a mirrored pair. These are great little devices for getting a decent number of spindles into a database server.
While they did that I installed the latest Release Candidate of VMWare Server 2.0 and went about setting up a Debian based Linux install with the latest MySQL 5.0 binary available. During testing we had some interesting processor affinity issues for the VM environment and after a very good experience and excellent responses in the VMWare community forums, I tweaked the config to have that VirtualMachine attach itself to processors 5-8 which correspond to all of the logical cpus on the second socket. This left the first socket’s worth of cpus for OS and IIS/ASP usage. Doing this would help avoid the cache issues that occur with multi-cpu systems and multi-threaded processes.
I ended up configuring the VM for 3.5GB RAM, 2 processors and tweaking the MySQL config to make good use of those resources for their INNOdb based tables.
The system has been running very reliably for over 2 months and is making very good use of the resources on that system. Load Average in the VM stays well under 1.0 and the cpus in the Windows system are easily handling all the different loads.
Overall I spent probably 8-10 hours installing and tweaking the config and helping them migrate their data. This was much less expensive to the other options and they got to make use of their existing hardware and software configurations.
A very positive experience and outcome.