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.)