The personal blog of Sam McLeod

CentOS 7 and HA

First some background… One of the many lessons I’ve learnt from my Linux HA / Storage clustering project is that the Debian HA ecosystem is essentially broken, We reached the point where packages were too old, too buggy or in Debian 8’s case - outright missing. In the past I was very disappointed with RHEL/CentOS 5 / 6 and (until now) have been quite satisfied with Debian as a stable server distribution with historicity more modern packages and kernels. I feel that CentOS / RHEL 7 has changed the game.* (When combined with ElRepo or EPEL that provide wide array of modern packages)

SSD Storage Cluster - Update and Diagram

Due to several recent events beyond my control I’m a bit behind on the project - hence the lack of updates which I apologise for. The goods news is that I’m back working to finish off the clusters and I’m happy to report that all is going to plan. Here is the final digram of the two-node cluster design: Plain text version available here This was generated from the LCMC tool (beware - it’s java!). More on this soon…

Continuous integration for the Linux Kernel - Built within Docker

Linux Kernel CI for Debian Github: sammcj/kernel-ci Those of us using technologies such as Docker and BTRFS or simply trying to gain a performance edge on the competition have a lot to gain from the features and performance of recent Kernel updates (especially from 3.18 onwards). ‘Enterprise’ Linux distributions such as RHEL & variants are concerningly out of date when comes to the Kernel. Many people seem to have forgotten what Linux is… Linux IS the Kernel. Someone said to me recently ‘Why do I need a more modern Kernel? - It never gives us problems!’ later in the conversation they alluded to a number of performance issues they were experiencing with both a database platform and with some modern containerised applications they were trying to run.

Xen Orchestra Docker Image

Docker config to setup XO which is a web interface to visualize and administrate your XenServer (or XAPI enabled) hosts Github: sammcj/docker-xen-orchestra Running the appUpdates are pushed to the Docker Hub’s automated build service: https://registry.hub.docker.com/u/sammcj/docker-xen-orchestra From Docker Hubdocker pull sammcj/docker-xen-orchestra docker run -d -p 8000:80 sammcj/docker-xen-orchestra Buildinggit clone https://github.com/sammcj/docker-xen-orchestra.git cd docker-xen-orchestra # Edit whatever config you want to change docker build -t xen-orchestra . See https://xen-orchestra.com for information on Xen Orchestra

Delete Government-Linked Certificate Authorities in OSX

Inspired by http://zitseng.com/archives/7489 Source (Github) WARNINGS Do not run unless you understand what this is doing The CA system is broken by design - This is not a fix for that This is merely a band-aid for those interested or concerned about these root CAs Usagechmod +x delete_gov_roots.sh ./delete_gov_roots.sh You’ll be prompted for your password as root access is required to delete system-wide root certs. See Also http://convergence.io https://addons.mozilla.org/en-US/firefox/addon/certificate-patrol/ https://github.com/kirei/catt https://www.eff.org/observatory https://bugzilla.mozilla.org/show_bug.cgi?id=478418 http://support.apple.com/en-us/HT202858 https://www.owasp.org/index.php/Certificate_and_Public_Key_Pinning

Building a high performance SSD SAN - Part 1

Over the coming month I will be architecting, building and testing a modular, high performance SSD-only storage solution. I’ll be documenting my progress / findings along the way and open sourcing all the information as a public guide. With recent price drops and durability improvements in solid state storage now is better time than any to ditch those old magnets. Modular server manufacturers such as SuperMicro have spent large on R&D thanks to the ever growing requirements from cloud vendors that utilise their hardware. The State Of Enterprise StorageCompanies often settle for off-the-shelf large name storage products from companies based on several, often misguided assumptions:

Direct-Attach SSD Storage - Performance & Comparisons

Further to my earlier post on XenServer storage performance with regards to directly attaching storage from the host, I have been analysing the performance of various SSD storage options. I have attached a HP DS2220sb storage blade to an existing server blade and compared performance with 4 and 6 SSD RAID-10 to our existing iSCSI SANs. While the P420i RAID controller in the DS2220sb is clearly saturated and unable to provide throughput much over 1,100MB/s - the IOP/s available to PostgreSQL are still a very considerably performance improvement over our P4530 SAN - in fact, 6 SSD’s result in a 39.

The Best Of - 2014 Edition

At the end of every year I note down a summary of the best applications, hardware & websites I’ve enjoyed & depended on throughout the year (and often for some time before). Info This post has long since been superseded. You can find the latest version of this post here. Software / General Use Fastmail - https://www.fastmail.com Evernote - https://evernote.com Reeder - http://reederapp.com Keynote - https://www.apple.com/au/mac/keynote Lastpass - https://lastpass.com Plex - https://plex.tv Calibre - http://calibre-ebook.com Software / Geek Use Sublime Text - http://www.sublimetext.com/3 Homebrew - http://brew.sh DropSync - http://mudflatsoftware.com Beets - http://beets.radbox.org Textual - http://www.codeux.com/textual XLD - http://tmkk.undo.jp/xld/index_e.html Code Academy - http://www.