Introduction

In order to run tests against what looks like a real cluster of Cassandra nodes, one wants to create multiple nodes and run them in parallel and run their software against that cluster.

So, I decided to create two racks on two separate computers. Each computer runs 3 VMs each run one instance of Cassandra. The VMs are installed with the most basic Ubuntu server (i.e. do not add anything when offered to install LAMP and other systems), Java, and Cassandra.

Network

Local Network

It is possible to setup a VM to make use of the local network (LAN). VirtualBox will ...

Just made a new addition to the project: snapwatchdog.

This is a daemon running in the background used to gather statistics about each server running in a Snap! cluster.

The statistics are saved in an XML file1 and already include the following information:

• CPU usage
  • Average load for 1, 5, and 15 minutes
  • Total usage in User, System, Idle modes
  • Total count of Page Cached and Swap Cache
  • Time when the system was last rebooted
  • Total number of ...

• 1. Ready to be processed by an XSLT stylesheet to present the results to the end user.

There is yet another update of libtld. This time the effective_tld_names.dat file included many new gTLDs, even some that are not yet, but will very soon be official.

It also included many corrections to existing country domain names such as .uk which is now available as a first level domain name, and .ve which changed quite a bit too.

There are also a few domains that were removed (now marked deprecated) such as 4 .us and 2 .ru sub-domains.

As per the list from Mozilla, there are quite a few new sub-domains used as main domain names by various businesses such as a few amazonaws and a new ...

Cassandra is very light weight, contrary to a standard database, they coin the safety of your data on the fact that it gets replicated many times, not on the fact that it gets transported safely between you and its journal and the drive.

There is a huge impact to that light weight though. Once in a while, the tables, or more specifically, a node journal get mangled. When that happens, you can continue to use Cassandra for any data that appears before the mangled data. This gives you the impression that everything works, when in fact, something is awry in that node.

An interesting side effect ...

When creating a dynamic website, the time it takes to create a page requires a proper (large enough) timeout or Apache will generate a 500 error even before the system has a chance to reply one byte.

Snap!, like many other content manager systems (CMS), will generate the entire page before sending anything back to the client. There are several reasons for doing this:

1. The system is generating HTML which we want to compress before sending it to clients;
2. The system likes to define the Content-Size header because it allows browsers to show clients how much of the data it already ...