cmdln.org (a sysadmin blog)

I know I’ve mentioned how much I love the sysstat package before. I use sar regularly to help with performance diagnostics (Analyzing Linux System Performance And Finding Bottle Necks, CPU Performance Analysis In Linux, Baseline Analysis Is Important, CPU Performance Analysis In Linux Revisited). I wrote this little Nagios plugin to collect the performance metrics that sar collects. (Read More)

If you hadn’t already guessed I am a big fan of the Xen hypervisor. Lately I have been using the Citrix XenServer release because it makes it quite palatable for my co-workers. One annoyance that I do have about XenServer is the requirement that you license it (with a free license) every year. If you fail to license it the GUI stops working. Now I hate relying on GUIs but the fact of the matter is others in my team expect to have a working GUI when they need to do something. And I dont know about you but I don’t really log onto the management console very often. Really I only log on to it if I need to provision a new server so its entirely plausible that a license would expire and I wouldn’t know about it until I really needed to do something. (Read More)

Have you ever had a machine that was a bit flaky? You know those ones that occasionally crash and don’t write anything useful into the log file. Sometimes you can capture those messages with netconsole. Just revisiting a small walk-through I wrote a while back. (Read More)

I like to have as little run in dom0 as possible. However some things you really need checked from dom0, like the status of your raid perhaps. Just some quick instructions on getting Nagios NRPE running in XenServer. (Read More)

Python has become my language of choice for automation and general scripting. Its nice to have an editor that makes things easier when your doing things. Its also nice to use an editor that you can find just about anywhere. I have customized my vim to make doing things in python much quicker and this is an old post where I talk about some of the modifications. (Read More)

This is just an old entry that I thought was interesting, and it appears its still relevant. Like a broken record, “economic times are rough”, what better way to boost your revenue than to exploit your customers. What better way to suppress a competitor than to increase a competitors infrastructure costs (with little visibility to boot). I did some repeated lookups this morning and got similar results. (Read More)

Another day, another flashback. I don’t know about you but at times I have had some very odd and uncomfortable requests from vendors. It’s not wholly  uncommon for them to want to log into your system to diagnose an issue for themselves. Or perhaps for whatever reason your manager says hey give this random outside person access to some important box. As a SA you get used to extremely odd requests and figure out how to just solve the problem. This flashback outlines what I did the last time I had to let an untrusted (note I had no reason to _not_ trust this person, but then again I also had no reason _to_ trust them) person have elevated privileges on a box of mine. (Read More)

Matt Simmons is trying to dust off some old articles he think some people may have missed. So I figure why not. A while back I talked about how to move a website (read DNS sucks , you need a reverse proxy). In fact I have talked about reverse proxies a few times since I tend to find them so useful. At any rate, this article stemmed from the first hand experience that opened my eyes to how bad DNS infrastructure really was. (Read More)

The last few days I have been having a pretty good debate with a friend about the virtues of open source vs Appliances. At times its gotten pretty heated but its all in good fun. The current debate centers around email infrastructure. There are options on the table to use an appliance, or a 3rd party service to control the spam. Of course I was appalled that SpamAssassin and brethren were not on the table. (more…)

Ewwww, scary isn’t it. No Its not Halloween, but you may have entered the twilight zone. Right, I never touch Microsoft products. Well in actuality sometimes I do (I just don’t brag about it). Some of the development at $work uses Microsofts Mediaroom, and I have a “Personal Server” (great name right?) that the developers use. I was trying to install the Mediaroom service pack yesterday and took some notes on the process. Some of my friends found it quite entertaining. I found it quite aggravating as you might imagine. (more…)