Assembly code from 1994, proto-DSL

Tonight I came across a chunk of x86 assembly code that I wrote for a university class in 1994. I present it here in its original form, complete with 1994 file modification date:

KSPOOL.zip

The thing I notice about this code in retrospect is that I used a macro (this was assembled with a macro assemler) to make some menu-key-dispatch code succinct and declarative in its appearance. This is quite low-level but in a sense not all that different from the “domain specific language” idea which has grown popular recently.

LVM (Logical Volume Management) – a very good thing

This Mailing list post from a user of “MythTV” reminded me of the wonders of LVM (Logical Volume Management) which is built in to Linux (HowTo, Resource page).  I first saw LVM years ago on a commercial Unix, and didn’t quite understand the point.  Now I see the point clearly, and set up most new machines with LVM.

If you’re not using LVM, and you have non-trivial storage hardware (more than one hard drive), now is the time to start.

On an OS without LVM built in (as I am, on my Windows machines..), it is often necessary to do things offline, with external tools (like Partition Magic) that could be done online in a running system with LVM.

St. Louis Code Camp – Lua Talk Notes and Source Code

At the St. Louis Code Camp on May 6, I gave a talk that was somewhat poorly titled “Painless Scripting with Lua”.  The topic more mostly about the overall use of scripting as a configuration and extension mechanism, with Lua as an example language.
The talk had no slides, only code and a 1-page handful with some notes. You can download the source code: 2006_code_camp_lua.zip and the notes follow:

Alternate Hard and Soft Layers Continue reading “St. Louis Code Camp – Lua Talk Notes and Source Code”

Basement Data Center

It occured to me today that a section of my basement is starting to resemble a data center:

Data Center

The four machines here:

  • Are all test machines, or being configured and burned in for future deployment – the production hardware for our projects invariably ends up in customers’ data centers or in robust colo facilities (redundant power, massive air conditioning, redundant “tier one” network connectivity, etc.)
  • All use AMD CPUs – two of them have dual-core Athlon64 X2’s.
  • Are all black – black is still the default color, it appears.

Other tidbits:

  • The leftmost machine is a “Shuttle XPC”.
  • The shelves are homemade and very strong.
  • Three of the machine run only Linux; the other dual-boots to Windows XP.
  • Very little work happens on these machine at the physical console – they are accessed via SSH, VNC, Terminal Services, etc.
  • There is a dedicated 15 amp circuit to run these machines.
  • The reason they are here, in my basement, is so that the hardware and OS can be configured. When one becomes wedged it can easily be rebooted or diagnosed at the terminal; that happens all to often when, for example, trying a variety of Linux kernels to get virtualuzation working .

Is my RAID working? HP / Compaq SmartArray RAID on Linux

One of our servers is an HP / Compaq 2U machine (DL380 ?) with 6 hard drives and the SmartArray hardware RAID controller. This generally works quite well, but we don’t use one of the handful of Linux distributions that HP supports… so from their site we find a great lack of information on how to administrate or monitor the RAID. It seems silly to me, in the Linux world, to offer such narrow support. Even if only a handful of distributions are fully supported, manufacturers ought to at least offer a page of tips and links for using their hardware with other distributions, offer non-distro-specific tool downloads, human-readable dependency lists, etc.

A while back I got the HP tools to install using “alien”, but these tools seemed overly complex for the simple, ongoing task of monitoring the health of the RAID arrays.

Today I found a simple answer: ArrayProbe, a free / open source tool from:

http://www.strocamp.net/opensource/

for monitoring, among others, SmartArray (CCISS) controllers.

Installation on this Debian system was a not as easy as it could have been. First, the dev tools:

sudo apt-get install gcc libc6-dev

Then I found that it requires the kernel sources (not just headers), in /usr/src/linux, which is not where they landed by default. With a minor “ln-s” workaround, the tool complies and runs fine:

root@servername:~# arrayprobe

OK Arrayprobe
All controllers ok

More details are available with command line options. The simple, one-line output is well suited to automated monitoring and notification – far more useful in many-server environment than a whizbang GUI tool.
Also, a great resource for finding Linux tools for hardware RAID administration and monitor is at http://developer.skolelinux.no/info/prosjektet/delprosjekt/hw-raid-info.html.

Update June 2007: Steve Cameron, maintainer of the CCISS Linux drivers, wrote to point out that the CCISS project now includes (through considerable effort) a cciss_vol_status tool which serves a similar purpose. cciss_vol_status emits somewhat more detailed status data, and might also make it “in the box” in Linux distros eventually, with the core CCISS. I’m unable to try it out myself – we’ve replaced that DL380 with commodity hardware and Linux software RAID.