Zach Shepherd's WordPress Blog

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Sunday, September 30, 2007

Debugging Long MySQL Queries

I’ve found myself debugging long (several hundred lines when written neatly) MySQL queries the past two nights, really wishing I had some tool that would allow you to step through the query (sorta like gdb, but for sql). If anyone knows of such a tool (or has any tips on preventing issues dealing with arithmetic involving NULL), I’d be interested to hear from you!

If anyone stumbled across this hoping for suggestions on how to handle this, check the comments to see if anyone had any advice for me. My only suggestion is to start at the deepest query/queries and work your way out…

posted by Zach at 11:25 pm  

Saturday, September 29, 2007

Project Management

A recent article on A List Apart made some interesting points about project management. The article, Hat Heads vs. Bed Heads, used the metaphors of “hat heads” (representing the management side of the project team) and “bed heads” (representing the creative side of the project team) to talk about how to manage projects at an overview level. While it’s an article mostly targeted at large development teams in an industry environment, much of the content is applicable to smaller teams and other environments. I’m not sure that I agree with all of the details, but it’s certainly an interesting perspective on the matter.

Edit – Looks like when I changed the wording of my second sentence, I didn’t do it very well.

posted by Zach at 12:08 am  

Saturday, September 15, 2007

Work done on the user storage image

My latest project is to get user storage up and running.

The first step was to get the image some space. A terabyte seemed like a nice round amount. It was just a matter of DDing an image file on animal, adding it to the rc.local for export (using vblade), configuring storage for AoE (adding aoe and dm-multipath to /etc/modules), mounting the image on storage, formating it, copying the contents of /home, and adding it to /etc/fstab.

The next step is to set up quota. The final step will be to develop a management interface for accounts and quotas.

posted by Zach at 8:57 pm  

Saturday, September 15, 2007

Software Freedom Day

In celebration of Software Freedom Day, the COSI held an open house style event. Student from Clarkson showed up, learned a little about the labs and about open source and had a little fun playing open source games such as Tremulous and looking at open source alternative to proprietary programs. Overall, it was a nice low-key celebration, although it’d be nice to see a bigger celebration next year.

posted by Zach at 7:08 pm  

Saturday, September 15, 2007


As an act of support for the open source project, I set up a tremulous server in a VM on 0011. It seems to be working alright. If anyone is interested in maintaining it, let me know, and I’ll set you up with an account.

posted by Zach at 2:34 pm  

Saturday, September 15, 2007

Making ubuntu images

I was working on setting up a tremulous server and ran into an issue involving libc6. Apparently etch doesn’t include the right version, but fiesty does. To use debootstrap to put fiesty on the images, I needed to first install the scripts on the blade:
$ cd /tmp
$ wget
$ dpkg --extract debootstrap_0.3.3.2ubuntu3_all.deb debootstrap-feisty
$ sudo cp debootstrap-feisty/usr/lib/debootstrap/scripts/{warty,warty.buildd,hoary,hoary.buildd,breezy,dapper,edgy,edgy.fakechroot,feisty,feisty.fakechroot} /usr/lib/debootstrap/scripts/

Then, it was just a matter of running the command to debootstrap the image (debootstrap --arch i386 fiesty /mnt/tmp

posted by Zach at 1:27 pm  

Saturday, September 15, 2007

SSH/NFS/Networking Issues on the Blades

Thanks to our resident (well, long distance) detective, Cyrus, the mystery seems to have been solved.

It turns out that the issue on the blades was being caused by them getting dhcp from Clarkson. It’s been an issue all along, but we didn’t notice it because of the 5 minute lease time (it would only effect us from the time Clarkson’s lease renewed one a day-ish until the time that Righteous’ lease renewed a maximum of 5 minutes later). When we changed our lease to be longer than Clarkson’s, our access became the one that only applied for the period between renewals.

The solution? Adding a prepend statement to the dhclient.conf to make sure our dns (Righteous) is always listed first in the resolv.conf. It turns out that this issue will effect anything that uses dhcp to get an address from Clarkson (the reason we weren’t getting the error on the virtual machines was that they were either statically configured or, in the case of the new ones, networking hadn’t been restarted since modification of the configuration files).

So far, so good. If this wasn’t the only issue, we should know in the next 24 hours.

Edit (Saturday Noon) – Still no issues; looking good so far.

posted by Zach at 12:01 am  

Thursday, September 13, 2007

Modifications to Cyrus’s Script

I (after consulting with Jeremy and Jake, as I’ve never before used perl) managed to update Cyrus’s script on animal to support images being exported over aoe (including exporting a script to be run on boot to export them). Adding images is now even easier!

posted by Zach at 8:27 pm  

Thursday, September 13, 2007

New images.

I had some free time, so I added a few more images (no, not photographs). Notable ones include one image ready to go for nagios (which Matt has already gotten up and running, at least on some level) and one ready to go for time (maybe a new member interested in getting involved could tackle this one).

posted by Zach at 7:57 pm  

Thursday, September 13, 2007

Open Source PDF Editing

I saw a link today on digg to an open source pdf editor. It’s something I’ve been keeping an eye out for for quite a while now. Finally found one. If anyone knows of any other ones, I’d appreciate hearing about it/them.

posted by Zach at 1:04 pm  
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