Overview

In this blog post we'll be covering setting up an SSD for Linux and then sharing the results of some performance testing.

What is an SSD?

SSDs are now well established as high performance alternatives to hard disks. Rather than using a spinning, magnetised disk and a tiny read/write head on the end of an arm, they are more like memory chips - completely "Solid State" Disks (no moving parts).

Britain is enjoying rather nice weather at the moment. One of our consultants has a CurrentCost meter and developed a plugin for Nagios using the excellent Nagios::Plugin Perl library. This allowed him to graph home current usage like this (spot when the electric oven was turned on):

Recently we've been involved in a project where a third party were due to supply hardware using their "standard configuration". Cutting the story short, this is how the hardware should have been setup prior to being handed over to us:

Hardware specification should be agreed upfront:

• Vendor
• Model
  • You may want to check compatibility
  • Not just of the server itself, but management features, components and peripherals
  • Perhaps match existing models, or alternatively wait until the next generation ships

Overview

Sometimes it's useful to have a console permanently logged in. That is without the usual username/password prompt. Naturally you are relying on just physical security here.

Howto

Edit /etc/inittab and find the lines like this:

3:23:respawn:/sbin/getty 38400 tty3


Change these to:

3:23:respawn:/sbin/getty -n -l /usr/local/bin/autologin 38400 tty3


Finally run

telinit q


That's it, nice and simple. Just ensure that you have a unique ID (the part before the first colon) and you've specified the correct terminal at the end.

Overview

Tracks is an Open Source GTD(Getting Things Done) program. Speaking personally, I'm a huge fan of Dave Allen's book - the GTD system and way of thinking has made me far more productive and effective. More importantly I feel so much more in control - no more worrying! GTD really requires some programs to allow you to use it - Tracks has worked very well for us.

How to

Memory is cheap. More than that it's also one of the most cost-effective ways to increase the performance of an application or server.

However virtual machines (particularly on hosted sites) are often charged according to memory usage so it is still useful to be able to trim your usage.

Here are some steps we took to reduce the usage on our virtual machines.

Tools

Overview

How to add paravirtualisation to CentOS v5.2.

Problem

In order to replicate a customer environment, we have some CentOS 5.2 virtual machines for development. However CentOS 5.2 does not feature any paravirtualisation and thus the performance of both the guest and host machines suffers.

Solution

By creating a custom Linux kernel with paravirtualisation support and making some adjustments to the initial ramdisk used for booting, we created a paravirtualised CentOS 5.2 machine.

Howto

First of all we must build the kernel: