Mark Sutton

Chief Technology Officer

As CTO Mark defines the technical strategy for CatN, designs and builds our key IT assets and engages with the IT community to communicate the CatN vision. You can find Mark on Google+

Process list for OpenVZ containers (vztop)

The standard linux task list shows you each process and the resources (e.g. CPU, Memory) that they are consuming. However, if you run top on an OpenVZ host server, it doesn’t show you the container ID of each process.

Fortunately, there is a tool imaginatively named, vztop, which can show you a slightly more useful list of container and host processes, along with their container ID. Read More

Choosing the right switch for storage

Storage over Ethernet is a hot topic in the web hosting datacentre at the moment. With several excellent storage protocols to choose from and plenty of vendors offering product there is certainly a lot of choice in the marketplace. But it’s easy to overlook the importance of the Ethernet switches that are going to be carrying your data – after all you just spent a fortune on ‘redundant’ storage right? Read More

Memtest Over Network

One rainy day we had a bad feeling that one of our rackable servers had corrupted memory. The server had some intermittent stability issues and hanged from time to time. It prompted us to test memory on all rackable servers in the rackable rack, especially that they were soon to become part of our hosting infrastructure.

If you ever tested memory you will most likely have heard about Memtest86 program. The procedure is simple, you just burn memtest.iso onto a CD and boot your server from it. Except that none of the rackables actually have CD-ROM drives. Read More

Resolving bind zone transfer issues

Today, a fax machine at the office started complaining that it couldn’t send emails. No useful error messages or anything…

After some digging it turns out the fax machine was getting SERVFAIL from the name server. This nameserver carries slaved zones for certain domains used for critical infrastructure, and it turns out there was a problem getting updates from upstream. Read More

Generator test: Wayne Horkan

Today we had the pleasure of swapping datacentre tours with Sun Microsystems. While we’re not quite on the same scale as Sun we always aim to impress and asked Wayne Horkan, their UK CTO, to perform our weekly generator test.

That means cutting off all mains power to the UPS suite and waiting for the black smoke and roar of our generator kicking in! Yes it worked, and there is nothing like throwing a datacentre kill switch to put a grin on any IT professionals face…

Read More