Bits and Chaos


Between bits and chaos, a sysadmin stands.

Review: Essential SNMP, 2nd edition

Last previous entry in this blog was one month ago, I’m unhappy with this but as I need to write down my Ph.D. dissertation by two or three months’ time I’m feeling the pressure and have very little time. But the life continues and goes on, so I’m still a Linux system administrator, and as such I feel that the most important skill I must develop is in the monitoring area. Only if you have a monitoring system that helps you track down software and, more important, hardware failures, you can successfully administer a large cluster of machines and being productive and pro-active, otherwise you’ll simply waste your time by fixing the today’s problem, and tomorrow will be another day with a tomorrow’s problem.
This may sound very common if you work in a corporate environment, but in Italy we have very few big customers, so the idea of monitoring is very well confined in some magic gardens where you are usually not invited. To learn the path for these gardens, I decided that this year I should focus on enterprise monitoring, and I started with the very basic of it, the SNMP protocol.
If you dig on the Internet for SNMP, you find some interesting tutorials, I greedily read them but I realized that I need something more robust and comprehensive. For my forma mentis (a latin expression that means shape/settings/idea of your mind, plus with no Wikipedia entry) I cannot successfully use a layer 7 tool if I don’t have a good idea of the communication protocol it will rely on. So I searched for an in-depth book and I finally landed on Essential SNMP, second edition from O’Really.
I found it’s an excellent book to understand what SNMP is and how it works, from the definition to packet sniffing on the network to see real data exchange. Also there are some real programming example if you want to write your own SNMP agent, so it’s a good starting point when you need to interact with an heavy customized environment.
But it’s a bit outdated, as every example in the book is about configuring and using HP OpenView, whilst open source tools like Nagios , Zabbix, Zenoss and OpenNMS have no more than some pages (if any) in the appendixes.
These tools, for what I’ve understand now, are usually hybrid, meaning that they covers both the hardware level monitoring function and the software one. Some of them, like Nagios, comes from application level monitoring and have some SNMP extensions, others are natively in the application layer and go deep in the stack, others were designed with the idea to cover both areas. They are very different in installation requirements, required configuration efforts, ease of maintenance. Some of them have a lot of plugins that makes the interaction with the hardware or the applications easy, some requires more tweaking. Even support is completely different, ranging from a free consultancy market to a single company that writes the software, give it to you for free, and try to made revenues from the support service.
So, to go back to the long term project, I think that I should understand how these oss solutions work, compare them, and deploy one or more of them to have a complete control over the infrastructure.

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