Archive
Posts from 2009
Slides from my centralized logging and syslog-ng presentation
I gave a talk tonight on syslog-ng, and how it can be used to build a centralized logging infrastructure. If you are interesting in learning more about how to deploy syslog-ng and create a centralized logging infrastructure, you might be interested in the slides I used during my talk. I would like to thank everyone who came out! It was a bunch of fun!
$ read more →How the Linux OOM killer works
Most admins have probably experienced failures due to applications leaking memory, or worse yet consuming all of the virtual memory (physical memory + swap) on a host. The Linux kernel has an interesting way of dealing with memory exhaustion, and it comes in the way of the Linux OOM killer. When invoked, the OOM killer will begin terminating processes in order to free up enough memory to keep the system operational. I was curious how the OOM worked, so I decided to spend some time reading through the linux/mm/oom_kill.c Linux kernel source code file to see what the OOM killer does…
$ read more →Viewing the status of NetworkManager managed links
As I mentioned in a previous post, I spent some time trying to get the NetworkManager to respect my custom DNS settings. When I was looking into this issue, I learned about the nm-tool utility. This nifty tool will print the status of each NetworkManager managed interface, as well as the connection state: I found the IPv4 settings section to be rather useful while I was debugging a network connectivity problem (nm-tool and ethtool make it SUPER easy to debug link problems), and will definitely be using this tool in the future!
$ read more →Scanning SCSI controllers for new LUNs on Centos and Fedora Linux hosts
While building out a new ESX guest, I had to scan for a new SCSI device I added. To scan a SCSI controller for new LUNs, you can echo the "- - -" string to the SCSI controller's scan sysfs node: Now you may be asking yourself, what do those three dashes mean? Well, here is the answer from the Linux 2.6.31 kernel source (I had to look this up to recall): As you can see above, the three values passed to the scan value are the channel, id and lun number you want to scan. The "-" equates to a wild card, which causes all of the channels, ids and luns to be scanned…
$ read more →Udev presentation slides
I gave a talk on the Linux udev device management framework tonight, and posted my slides to the presentation section of my website. Thanks to everyone who came out! I had a blast presenting, and enjoyed meeting some new folks!
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