Following on from our earlier article about upgrading from a traditional hard disk to an SSD, we tested that old metric, boot time.

We used the excellent bootchart tool to gather these statistics. It's worth noting that time for the BIOS to post takes quite a long time (about another 30 seconds). We are only timing from kernel load to end of startup.

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).

For centralised authentication and authorisation, LDAP is the de-facto standard. Whether in its pure form on Unix or in Active Directory guise on Windows, everyone uses it.

What many people don't realise is that you can store all sorts of useful (and not so useful) information in LDAP. One field which can be useful is the "manager" attribute. One of our customers use that and so we've written a small script to graph it using the excellent Graphviz tool.

In this second article we'll be taking a look at the dashboard itself. Six months ago we were distinctly underwhelmed by the dashboard - it was more style than substance.

More recently we tried it and found various bugs including a lack of sort which resulted in this amusing graph:

It's been exactly six months since we wrote our first Puppet dashboard article and it seems that an update is due.

In this first article, we'll cover installing puppet dashboard on a Debian Lenny server as that is where our puppet server currently runs.

• first of all you will probably need a newer version of the rails framework - use lenny-backports for this:
  • apt-get install -t lenny-backports rails

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):

Sadly this isn't to be a blog of joy, more a blog of "must do better".

Today we upgraded one of our servers from Ubuntu Hardy (8.04 LTS) to Lucid (10.04 LTS) and we hit a few issues.

First of all, we carefully read the Release Notes, nothing of relevance there.

We then followed the Upgrade process. This went fine for a little while but then it started to fail badly - any package install failed with:
 

A relatively new term "Devops" is starting to become more widespread. As with most new terms it means different things to different people (a bit like "the cloud" or "grid computing" does even now).

Here at Bitcube we use KVM as our preferred virtualisation platform. It has the best Linux support and is the standard for all Linux distributions. Whilst it still shows a bit of immaturity at times, there is an upside - rapid development and improvements.

Wonderful though Puppet is, it can be frustrating when it spits out an error message which makes no sense.

We could keep all this useful information to ourselves, however we are a caring, sharing company and so we've spilled the beans.

Without further ado, please see our guide to Puppet errors.