Highly redundant array configuration
The cost of storage arrays is falling along with the quality of their manufacture. To quote Lev Andropov from the “Armageddon”: “Components. American components, Russian Components, ALL MADE IN TAIWAN!” What in the nineties used to be quality storage hardware from Sun, these days is a bunch of consumer-quality hard drives thrown together into a [...]
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23. April 2008
AI Research: Playing Mind Games
The news of Artificial Intelligence research always attracted my attention. Whenever this subject comes up on Slashdot, I just can’t resist posting a comment. The desire usually is to dump a bucket of cold facts onto the fire of wild imagination. The recent such occasion presented itself with the discussion of the “Two AI Pioneers. [...]
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21. April 2008
Your unsecured Wi-Fi network
Network World reports this week that, according to a study by Accenture, some twelve percent of computer users are connecting to some else’s unsecured Wi-Fi networks. So here’s the question I wanted to discuss: is this illegal and, if so, then who is breaking what law? Let’s start with a simple scenario. The other day your [...]
Continue reading...15. May 2008
VxVM Recovery Cheatsheet for Solaris
This is a quick-and-dirty guide to recovering VxVM volumes and filesystems on a Solaris server. These instructions are not intended to be an in-depth troubleshooting guide for the Veritas Volume Manager. This is just something to try if your VxVM volumes did not come up. A possible scenario would be: you rebooted your Sun box [...]
Continue reading...4. May 2008
Improving WordPress Performance
WordPress is a great blogging engine and decent CMS. Unfortunately, most available WordPress themes- even those claiming to be “minimalist” - are bloated and slow to load. Heavy CSS stylesheets, multiple Java scripts, numerous graphics files - all of these elements are relatively small in size, but there are many of them. About 80% of the [...]
Continue reading...1. May 2008
Use Perl inside Shell scripts
Perl is a far more powerful programming tool than any shell script. Sometimes you want to borrow some of that power without having to rewrite your entire shell script. There is an easy way to integrate Perl snippets inside your shell script.
Continue reading...27. March 2008
Convert MySQL table to CSV file
CSV is a field-separated format that can be easily imported into a spreadsheet application. Usually the separator field is a comma. However, sometimes it is easier to select a more unusual character (like “@” for example), so that the field separator is not confused with commas in the field values. In the example below we will [...]
Continue reading...25. March 2008
Installing and Configuring Ganglia
Ganglia is a distributed performance monitoring application used primarily for tracking status of high-performance compute (HPC) clusters. Ganglia is a royal pain in the ass to install and configure even for a seasoned Unix sysadmin. First, some basics about Ganglia-related pieces of the puzzle: rrdtool The glorious Round Robin Database package. This needs to be installed on [...]
Continue reading...24. March 2008
Dealing with ReiserFS bad blocks
The following is a procedure for recovering a ReiserFS filesystem with bad blocks. If this is a system FS and cannot be unmounted, the box needs to be booted from the latest version of Knoppix Live CD that has ReiserFS tools available. Determine the blocksize for your device (default is 4096): debugreiserfs <device> | grep -i ‘blocksize’ Scan [...]
Continue reading...21. March 2008
ReiserFS Filesystem Recovery
The this is a description of a method for recovering ReiserFS filesystems from failed disks with bad blocks, when other recovery methods (reiserfsck) will not work. For this example, the failed server is called node1 and the bad drive is /dev/hda1 Connect to the server and create an image of the affected disk on the /destination_fs [...]
Continue reading...11. March 2008
Log Monitoring with Swatch
Swatch is a Perl-based log monitoring tool that can match regular expressions and perform automated actions. The tool is useful for monitoring system log files in real time with an option to run external commands or to notify the admins in response to particular messages found in the logs. Example configuration file: /etc/swatch.conf watchfor /bvebw3/ echo bold throttle 0:2:0,use=regex bell [...]
Continue reading...9. March 2008
Linux User Activity Management
The following is a detailed look into managing Linux users and the system resources they utilize. Disabling user access; halting, killing, and re-nicing user processes; controlling disk space allocation are all points covered by this article. Halting, Resuming, and Killing users Before taking any of the actions below, you may want to notify the user: write alex pts/67 [...]
Continue reading...27. February 2008
Veritas Cluster Troubleshooting
Veritas cluster server is a high availability server. This means that processes switch between servers when a server fails. All database processes are run through this server - and as such, this needs to run smoothly. Note that the oracle process should only actually be running on the server which is active.
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Asides 
Computers kill. That’s right: according to the National Highway Traffic Safety Administration, some 2,600 die every year in car accidents because they got distracted by their cell phone, a GPS gadget, an MP3 player, or a PDA. In fact, the leading cause of death among Americans is heart attack; stress and obesity are the leading causes of heart attacks; and computer technology is one of the leading causes of both stress and obesity. US Department of Labor reports that Repetitive Stress Injury accounts for 60% of all job-related illnesses, costing businesses some $20 billion annually. Computers are the leading cause of Repetitive Stress Injuries such as carpal-tunnel syndrome. According to AMA, computers are responsible for nearly 63% of all vision disorders. This is why computer software is so buggy: experienced programmers are overweight, stressed out, half-blind and can’t move their wrists.
8. May 2008
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