Archive for September, 2009

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 […]

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: $ nm-tool […]

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: $ echo “- – -” > /sys/class/scsi_host/host0/scan Now you may be asking yourself, what […]

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!

Getting the Linux NetworkManager process to respect custom DNS server settings

I recently switched my work Desktop from Ubuntu to Fedora 11, and noticed that there are some new configuration options now that network intefaces are managed by the NetworkManager process. Two useful options are the ability to specify the DNS servers and search domains in the network-scripts files, and have those applied when a DHCP […]

Listing packages that were added or updated after an initial Fedora or CentOS installation

I was reviewing the configuration of a system last week, and needed to find out which packages were added after the initial installation. The rpm utility has a slew of options (you can view the list of options by running `rpm –querytags | more`) to query the package database, including the extremely handy INSTALLTIME option. […]

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