Graylog2 is an open source log management solution that stores your logs in MongoDB. It consists of a server written in Java that accepts your syslog messages via TCP, UDP or AMQP and stores it in the database. The second part is a web interface that allows you to manage the log messages from your web browser. Take a look at the screenshots or the latest release info page to get a feeling of what you can do with Graylog2.

The web interface
All data sent to Graylog2 will appear in the web interface. Use the web interface to search and filter your data. A core part of the web interface are streams: They basically are saved searches that allow you to quickly access an overview that is already pre-filtered to match for example specific parts of your application. You can also run monitoring and alerting on single streams or directly forward all messages that are matched into a stream to other endpoints.

How do I send my log data?
The Graylog2 server accepts standard syslog via TCP/UDP and GELF via UDP. You can also send in both formats via AMQP (AMQP Docs). You can configure your syslog daemons to send their data to Graylog2 or log directly from within your applications. (more…)

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What’s an inode?


In the electronic pages of Linux Magazine, file systems are commonly discussed. It’s a fact! In these discussions you might see the term “inode” used in reference to a file system. Fairly often people ask the question, “what is an inode?” so that they can understand the discussion (remember, there is no such thing as a bad question – at least for the most part).

To many people who read these storage articles this might seem like an elementary question but for many people just starting in Linux this concept may not be understood. Plus it’s always good to review the concept but let’s keep any comments civil and constructive (especially if they are directed at the author). Let me also state that I’m not a file system expert so please correct any misstatements but also please give references so people reading the comments can explore the topic.

File systems in general have two parts:

(1) the metadata or the “data” about the data, and

(2) the data itself. The first part, the metadata, may sound funny because it’s data about the data, but this is a very key component to file systems. It consists of information about the data. More precisely it includes information such as the name of the file, the date the file was modified, file owner, file permissions, etc. This type of information is key to a file system otherwise we just have a bunch of bits on the storage media that don’t mean much. Inodes store this metadata information and typically they also store information about where the data is located on the storage media. (more…)

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