Category Archives: Tech

Tech

Oops!

First night on the new web server and one of my php scripts filled the logs with error messages. Back up now.

Leaving Linode

Today, I have shut down my primary web server running on Linode. Linode provides virtual servers, and have been doing so for a long time. Before Xen and KVM and VMWare (etc) were available and popular, Linode pioneered virtual servers using something really cool called User Mode Linux, wherein Linux runs as a program inside Linux on the host system.

I used Linode for a while when they were running User Mode Linux, transitioned to shared web hosting for a while when my needs were not so sophisticated, and then came back to Linode for about three years, running at times 4-5 virtual servers.

Recently, I found good, local colocation, ran the numbers on running my own server, and am now running this site and many others from the one server. It’s a little scary running all this stuff myself and depending on it. I have some backups in place but once I settle in I will probably buy another server and set up some kind of failover. Ultimately, at this point in my life I’m doing HPC consulting and I know the hardware and software stacks used in enterprise computing, so I’m much better off than when I was running an FTP and webserver from under my bed in my dorm room on a Pentuim 100 MHz.

Nonetheless, I’m sure there will still be some glitches now and then as I work out the new setup. Here’s hoping they’re nothing major. Just in case, I’m dumping an image over SSH at this very moment from my old Linode to the storage on the new server. If I’m ever really stuck I can always push it back up there to a new account. I also have my account until the end of the month, so that’s a bit of a safety net.

I’ve always been very happy with Linode. It’s a polished operation and they really know their stuff. They don’t oversell their capacity or other shady things like that. The only complaint I have is their recent security issue with the Linode Manager, and I think they handled that pretty well. I’d readily recommend them to others or go back to them in the future if necessary.

So long, Linode!

Getting a Linux Kernel changelog using git

I am setting up my new webserver (which, incidentally, this post is being written on), and had some trouble with the version of the Linux kernel I was using. I wanted to see whether my problem had been fixed between my kernel version and the current one, but couldn’t find an easy way to do that. User Octayn in ##linux on freenode IRC suggested I use git with tags. A little googling suppiled the right command-line magic.

First, I cloned the linux-stable git:


git clone git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git

Then, after changing into the linux-stable directory, I checked the tag names available:


git tag -l | less

That showed me the formatting of the tags, namely v. So then the command to get the full changelog was:


git log --decorate v3.0.9..v3.0.32

I did find some commits that might have fixed my problem. I upgraded and so far, so good. Only time will tell.

This is here as much for my own reference as it is for yours, but I hope it helps you!

delayacct and iotop in Ubuntu 10.04 Lucid Lynx

I was trying to use iotop yesterday on my workstation and it was complaining that “CONFIG_TASK_DELAY_ACCT” was not enabled in the kernel. “OK,” I thought, “I can rebuild the kernel, no problem.” So I went to rebuild the kernel and discovered that CONFIG_TASK_DELAY_ACCT was already enabled along with the associated config options needed for iotop, so I was confused.

After a little spelunking of old mailing list entries (which I am trying to spare you with this post, dear reader), I discovered that the Ubuntu folks flipped around how the “nodelayacct” kernel boot parameter works for various arcane reasons. Here’s the short version of how to enable it.

1) Edit /etc/default/grub, adding “delayacct” as an option to the GRUB_CMDLINE_LINUX_DEFAULT entry. If you hadn’t already modified that line, it would go from


GRUB_CMDLINE_LINUX_DEFAULT=""

to


GRUB_CMDLINE_LINUX_DEFAULT="delayacct"

2) Run “sudo update-grub”
3) Reboot, and you should be good to go