Well as you may know, I had to support my thesis yesterday (July 16) in Arequipa – Peru, at “Universidad Católica de Santa María”. I’ve been approved and finally I became an engineer in Systems Engineering.
As I said in a previous post, my thesis was about High Availability Clusters. Actually, it was about designing a Model to Implement High Availability Cluster for Web Servers. My model consists on three Layers, which provide fault tolerance (High Availability) and scalability. Everything was done using 6 Ubuntu Servers virtualized on VMWare.
Layer 1 consists in two servers in an active/passive mode. This Layer provides fault tolerance, which can be interpreted as high availability, but does not provide scalability. I used LVS (using DIrect Routing) to load balance between Web Servers on Layer 2. I also used Heartbeat, ipvsadm and ldirectord.
Layer 2 consists in 4 Web Servers (can be more), in an active/active mode. This layer provides high availability and scalability. This layer also allows us to use every kind of web server (including Windows Server), because load balancing is done in Layer 2 of OSI Model (thanks to the Direct Routing method).
And layer 3 consists on two servers in an active/passive mode, to provide data access. Here I used NFS and MySQL, to provide file access and database access on both servers, and I used DRBD to provide data replication between them. The monitoring was done by using Heartbeat. This layer also provides fault tolerance but not scalability. To provide fencing in this layer I used meatware, which is provided by STONITH for heartbeat.
As you can see, this is a classical implementation of High Availability Clusters using LVS. For some of you might be an everyday thing, but not here in Peru. This is because because there aren’t lots of organizations and companies, or even Linux experts, who know how to implement Linux based clusters (besides banks). My thesis allows those who want to know how to create them, and shows that Microsoft and Red Hat, are not the only OS’s where we can create High Availability Clusters. This also shows how powerful is DRBD when we don’t have the possibility to work with SANs or other data storage technology.
Thanks to all the developers who created these great tools, that allows us to create Linux Based High Availability Clusters, and also thanks to the Ubuntu Community to provide these packages. This made my life easier .
And well… now i’m unemployed and with nothing to do but contribute to Ubuntu (I guess i’ll search a job as a Sysadmin or Network admin). But finally i have more time to concentrate myself to learn more about Ubuntu Development.