Citrix Archives - trefor.net

We have stepped up our use of Virtual Machines at network level at Timico and recently rolled out a significant number of Xen based platforms. Xen (see Xen.org). For those that don’t know a Virtual Machine is a virtual server that can run on multiple hardware devices simultaneously but can be seen as a single entity by the network.

Because the company has been growing the need to scale up easily has become more and more pressing. Over the Christmas break (the Network Operations team is allowed two hours off for Christmas lunch which they take communally in the kitchen at the NOC 🙂 ) a new email platform was rolled out on Xen based hardware. As the burden of mail inevitably grows all Timico will have to do is add new hardware capacity with no need for network downtime or reengineering.

The beauty of Xen is that it takes very little time to add capacity to a server farm and downtime is minimal or non existent. You can therefore move a service from a small machine to a more powerful one with perhaps as little as 60 milliseconds interruption.

All new servers are rolled out with Xen now at Timico. Whilst Xen is open source and therefore free Citrix does sell a commercial version. If you have no skills in this space it could be an option but otherwise drop me a line if you want any advice on the subject.

At Timico we recently installed a complete network solution for a customer in the UK. The requirement included installation of a domain controller, file and print server, Microsoft Exchange 2007, Microsoft SQL server various databases and for their document management system and a Citrix ZenApp for home workers to run the document management system remotely.

The company also needed to store lots of documents. They have a paperless office and all documents are scanned in by the document management system which required a redundant Storage Area Network (SAN).

100% uptime or as near to this as possible was also wanted but this came in tandem with a fairly tight budget which isn’t always consistent with high reliability.

The architecture that the Timico team came up with involved running all servers and the SAN in a virtualised environment. In this way the design challenge could be met by using only two physical servers called nodes that provided a fully load balanced and virtually clustered redundant solution.

By doing it this way we saved rackspace (5U) and power and 2 servers – we would otherwise have been looking at a pair of virtual servers and a pair of SAN servers.

Did it work? In the first week a hardware problem caused one of the 2 server nodes to temporarily fail. This was picked up by Timico’s monitoring desk but the customer, however, did not notice or experience any loss of service.

I’m Virtually Certain that this is the way forward.