Improving mod_perl Driven Site's Performance -- Part I: Choosing Operating System and Hardware Page 4

Free and Open Source OSs are probably less susceptible to this kind of problem. Development is usually distributed between many companies and developers, so if a person who developed a really important part of the kernel lost interest in continuing, someone else will pick the falling flag and carry on. Of course, if tomorrow some better project shows up, developers might migrate there and finally drop the developmentr; but in practice people are often given support on older versions and helped to migrate to current versions. Development tends to be more incremental than revolutionary, so upgrades are less traumatic, and there is usually plenty of notice of the forthcoming changes so that you have time to plan for them.

Of course with the Open Source OSs you can have the source code! So you can always have a go yourself, but do not under-estimate the amounts of work involved. There are many, many man-years of work in an OS.

Keeping up with OS Releases

Actively developed OSs generally try to keep pace with the latest technology developments, and continually optimize the kernel and other parts of the OS to become better and faster. Nowadays, Internet and networking in general are the hottest topics for system developers. Sometimes a simple OS upgrade to the latest stable version can save you an expensive hardware upgrade. Also, remember that when you buy new hardware, chances are that the latest software will make the most of it.

If a new product supports an old one by virtue of backwards compatibility with previous products of the same family, you might not reap all the benefits of the new product's features. Perhaps you get almost the same functionality for much less money if you were to buy an older model of the same product.

Choosing the Right Hardware

Sometimes the most expensive machine is not the one which provides the best performance. Your demands on the platform hardware are based on many aspects and affect many components. Let's discuss some of them.

In the discussion I use terms that may be unfamiliar to you:

• Cluster: a group of machines connected together to perform one big or many small computational tasks in a reasonable time. Clustering can also be used to provide 'fail-over' where if one machine fails its processes are transferred to another without interruption of service. And you may be able to take one of the machines down for maintenance (or an upgrade) and keep your service running--the main server will simply not dispatch the requests to the machine that was taken down.

• Load balancing: users are given the name of one of your machines but perhaps it cannot stand the heavy load. You can use a clustering approach to distribute the load over a number of machines. The central server, which users access initially when they type the name of your service, works as a dispatcher. It just redirects requests to other machines. Sometimes the central server also collects the results and returns them to the users. You can get the advantages of clustering too.

• Network Interface Card (NIC): A hardware component that allows to connect your machine to the network. It performs packets sending and receiving, newer cards can encrypt and decrypt packets and perform digital signing and verifying of the such. These are coming in different speeds categories varying from 10Mbps to 10Gbps and faster. The most used type of the NIC card is the one that implements the Ethernet networking protocol.

• Random Access Memory (RAM): It's the memory that you have in your computer. (Comes in units of 8Mb, 16Mb, 64Mb, 256Mb, etc.)