You want an OS with good memory sharing capabilities. If you preload
the Perl modules and scripts at server startup, they are shared
between the spawned children (at least for a part of a process’ life –
memory pages can become ”dirty” and cease to be shared). This feature
can reduce memory consumption a lot!
And of course you don’t want an OS that doesn’t have memory sharing
The Real Cost of Support
If you are in a big business you probably do not mind paying another
000 for some fancy OS with bundled support. But if your resources
are low, you will look for cheaper and free OSs. Free does not mean
bad, it can be quite the opposite. Free OSs can have the best support
you can find. Some do.
It is very easy to understand – most of the people are not rich and
will try to use a cheaper or free OS first if it does the work for
them. Since it really fits their needs, many people keep using it and
eventually know it well enough to be able to provide support for
others in trouble. Why would they do this for free? One reason is
for the spirit of the first days of the Internet, when there was no
commercial Internet and people helped each other, because someone
helped them in first place. I was there, I was touched by that spirit
and I’m keen to keep that spirit alive.
But, let’s get back to our world. We are living in material world,
and our bosses pay us to keep the systems running. So if you feel
that you cannot provide the support yourself and you do not trust the
available free resources, you must pay for an OS backed by a company,
and blame them for any problem. Your boss wants to be able to sue
someone if the project has a problem caused by the external product
that is being used in the project. If you buy a product and the
company selling it claims support, you have someone to sue or at least
to put the blame on.
If we go with Open Source and it fails we do not have someone to
sue… wrong — in the last years many companies have realized how good
the Open Source products are and started to provide an official
support for these products. So your boss cannot just dismiss your
suggestion of using an Open Source Operating System. You can get a
paid support just like with any other commercial OS vendor.
Also remember that the less money you spend on OS and software, the
more you will be able to spend on faster and stronger hardware. Of
course for some companies money is a non-issue, but there are many
companies for which it is a big issue.
Ouch… Discontinued Products
The OSs in this hazard group tend to be developed by a single company
You might find yourself in a position where you have invested a lot of
time and money into developing some proprietary software that is
bundled with the OS you chose (say writing a mod_perl handler which
takes advantage of some proprietary features of the OS and which will
not run on any other OS). Things are under control, the performance
is great and you sing with happiness on your way to work. Then, one
day, the company which supplies your beloved OS goes bankrupt (not
unlikely nowadays), or they produce a newer incompatible version and
they will not support the old one (happens all the time). You are
stuck with their early masterpiece, no support and no source code!
What are you going to do? Invest more money into porting the software
to another OS…