Coldharbour Digital has gained substantial experience working with Linux and UNIX-like operating systems over a period of more than 28 years.

Our work with Linux dates from 1999, and includes kernel configuration and assembly of a complete Linux distribution from scratch. We have considerable experience in Linux system administration, including application packaging, having packaged several hundred bioinformatics applications for Red Hat Enterprise Linux.

Our work with UNIX dates from 1988, when we developed a system level service for checkpointing of user processes on DEC Ultrix, just one of many examples of UNIX system programming.

We have considerable experience with ZFS on Linux as a highly cost-effective solution for science compute storage on commodity hardware. For high performance, a scale-out approach is required, with a number of servers sharing the load. We have experience with such systems, with approaching a peta-byte of total storage.

Coldharbour Digital has been engaged in DevOps since before the term was invented, mostly in Linux environments.

What is DevOps?

DevOps is what happens if you ask a software developer to perform system administration and infrastructure management. Rather than working on the level of configuring individual servers, the focus is on development of the site configuration manifest, which is applied in a uniform and automated way to all servers.


With DevOps, everything is:

  • uniform
  • automated
  • scalable
  • inherently documented

Uniformity of server configuration is a key way to reduce infrastructure management costs, by eliminating ad hoc differences between servers. Once a system is working, it stays working.

Better, stronger, faster, for significantly less than 6 million dollars.


Server configuration management is performed using tools such as Puppet, Chef, Salt, Ansible, or CFEngine. At Coldharbour Digital, our favourite is Puppet, but any of these is a huge improvement over a manual approach.

Configuration is contained in a central side-wide manifest, kept under configuration control. For configuration control, we recommend a modern revision control system such as Git or Mercurial.

Server deployment is a critical aspect of infrastructure management. This can be fully automated through PXE boot over the network, using kickstart files. Cobbler is a key tool for managing kickstart installation and initial configuration from manifests that we have found to be extremely beneficial.


Coldharbour Digital has experience with computer and network security frameworks and implementation.

Best Practice

Our work in this area is informed by leading experts: Ross Anderson ("Security Engineering"), Steve Bellovin ("Thinking Security"), and Adam Shostack ("Threat Modeling").

We have experience with the Center for Internet Security recommendations for Red Hat Enterprise Linux, both Level 1 and Level 2, including firewall configuration, advanced SELinux customisation, and intrusion detection.


Coldharbour Digital has vast experience in software development, in a variety of languages, environments, and application domains.

We are well versed in Go, JavaScript, C, C++, Java, Ada, Python, Perl, Haskell, Smalltalk, Git, Mercurial, ClearCase, X/Motif, UML, Rational Rose, Teamwork, Linux and various Unix, VxWorks and both object oriented and functional programming techniques.

We have used many different development methodologies, from classical waterfall, through iterative (Rational Unified Process), and agile. Latterly, so-called agile methodologies seem to us to have become very much less agile than was originally envisaged. Our preference these days is for Kanban, as described by David J Anderson in his book of the same name.



Coldharbour Digital was founded in 2015 by Simon Guest.

Simon graduated from the University of Cambridge with an MA in Mathematics and a Diploma in Computer Science. He started his career in 1989 in the United Kingdom, where he worked as a programmer for Praxis High Integrity Systems. His rigorous mathematical background and early work on high integrity systems for air traffic control were an integral part of the development of his high discipline approach to industrial-strength software development and system administration.

Simon's later roles included software development team leading in Siemens UK Research Centre at Roke Manor during the 1990s and early 2000s, working in mobile telecommunications and computer networks.

Since 2008, Simon has been living and working in New Zealand, where his roles have included working as a senior consultant within AgResearch, with responsibility both for the High Performance Compute environment, and for the company IT security framework.


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