Chapter II. What’s new in Cassandra PV Archiver 3.x

Table of Contents
1. Cassandra PV Archiver 3.0
1.1. Cassandra PV Archiver 3.0.1

1. Cassandra PV Archiver 3.0

The Cassandra PV Archiver 3.0 is intended as a replacement for the Cassandra Archiver for CSS 2.x. While sharing some of the concepts with the Cassandra Archiver for CSS 2.x, the code for the Cassandra PV Archiver 3.0 has actually been rewritten from scratch. The Cassandra PV Archiver 3.0 uses a new, CQL-based storage architecture that provides a significant improvement in performance and also simplifies the structure of the stored data, enabling direct data access for special applications. Unfortunately, this means that data archived with the Cassandra Archiver for CSS 2.x is not compatiable with the Cassandra PV Archiver 3.0 and has to be converted manually.

In addition to the change of the data format, the Cassandra PV Archiver 3.0 brings many new features that make it more scalable and simplify the deployment and operation:

  • Completely new web interface for monitoring and configuring the archive cluster.
  • Changing the configuration of channels (including renaming channels and moving channels between servers) without having to shutdown archiving servers.
  • Asynchronous sample writer, making the best use of multi-core CPUs.
  • Web-service interface for accessing the archive, simplifying the deployment of clients.

As the list of changes is so vast, even users already familiar with the Cassandra Archiver for CSS 2.x are strongly encouraged to read the complete manual of the Cassandra PV Archiver 3.0.

1.1. Cassandra PV Archiver 3.0.1

Version 3.0.1 is a bugfix release that fixes three bugs in the archive-access JSON interface. The first bug caused an exception when trying to retrieve enum samples, making it impossible to retrieve such samples via the JSON interface. The second bug caused incorrect values to be sent when an enum sample had more than a single element. The third bug concerned the serialization of the special “disabled” and “disconnected” samples. Those samples where always presented with a quality of “original”, even if they actually were decimated samples and should thus have had a quality of “interpolated”.

All the bugs fixed in this release only concern the archive-access interface. This means that data written by previous releases has not been affected by the aforementioned bugs and is correctly serialized after installing this update.