Today I was working on one small consulting task and our client asked for an upgrade from MySQL 5.0 to 5.1. It was pretty easy and task was successfully finished and reported to the customer… But few hours after my report I’ve got an email from customer with something like “WTF? Where is my 5.1?!”. I was shocked when I saw happily running 5.0 on their server w/o anything related to my 5.1 installation…

After some short investigation I’ve found out, that it was cpanel (dumb software for dumb system administrators) - it noticed, that installed mysql version (5.1) is not the same as it thought it should be (5.0), so without any warnings or notices it removed all 5.1 rpms and installed “brand new” 5.0.

Here I’d like to say GREAT THANKS to mysql team for such a great software which did not screwed up user’s data in such situation. But what idiots in cpanel development team decided, that is it appropriate and …

Recently I had one customer for consulting and aside from mysql optimization, etc they asked me for cacti installation/setup to monitor their pretty generic LAMP application. I’ve started setting up all this stuff and I’ve never thought it could be so painful… lots of different templates for the same tasks, all of them are incompatible with recent cacti releases, etc, etc… So, this post is generally a list of used templates with a fixes I’ve made to make them work on recent cacti release.

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This weekend I was doing some development for one of our projects and we needed to make screenshots of a web pages (see my next posts about this task). I’ve managed to develop small piece of code which uses GtkMozEmbed component (Mozilla Gecko-based renderer for web pages) to create screenshots of any page, but there was some problem… The problem was a following: GTK+ library can’t work w/o fully-functional X server running on your machine. Obviously I didn’t want to run such software (no monitor/keyboard/mouse, dumb graphics adapter on the server, etc, etc) so I’ve tried to find some solution… And in this tiny article I’ll describe the method I’ve managed to find.

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This week aside from tons of different tasks I was working on one of MMM users complaint regarding some issues with MMM on Solaris 10. I knew that this OS has not so user (admin) friendly environment (especially for people with strong GNU-related background), but had no other options and decided to install Solaris 10 in VMWare Fusion on my desktop.

Installation was a bit strange comparing to Debian/RHEL/Ubuntu and FreeBSD where I have a strong experience, but I’ve managed to install it successfully. The major problem after my first boot was a lack of knowledge about how things could be done in Solaris… Below I’ll describe what generic Linux admin could do with Solaris to make it easier to use and more friendly for GNU-addicted mind

Notice: If you’re …

Few days ago I worked on some customer’s server and there was a problem - their nfs server went down and we were forced to change some settings on their FC4 clients to prevent shares from dieing because of kernel bug. But when we’ve changed settings in /etc/fstab there was one more step before task was completed - we need to remount this share (I mean unmount/mount). But how to perform this operation if there are some processes in D (non-interruptible sleep) waiting for dead share and prevent it from unmounting? They wait because of hard option on the share and lack of intr option and any unmount request would produce a following results:

streaming01:~# umount /storages/2
umount: /storages/2: device is busy
umount: /storages/2: device is busy

So, here is a list of steps you need to do to be able to remount your share.

First of all, you need to send KILL(9) signal to all you processes …

If you’d take a look at any web site, you will notice, that almost all of the pages on this given site are pretty static in their nature. Or course, this site could have some dynamic elements like login field or link in the header, some customized menu elements and some other things… But entire page could be considered static in many cases.

When I started thinking about my sites from this point of view, I understood, how great it would be to be able to cache entire page somewhere (in memcache for example) and be able to send it to the user without any requests to my applications, which are pretty slow (comparing to memcache ) in content generation. Then I came up with a pretty simple and really powerful idea I’ll describe in this article. An idea of caching entire pages of the site and using my application only to generate small partials of the page. This idea allows me to handle hundreds of queries with one server running pretty slow …

Few days ago I’ve started migration of some of my non-critical servers to Debian Etch (from Sarge). Just after first apt-get update && apt-get dist-upgrade, when apt has been upgraded, I noticed really strange (as for me) error: when I’ve tried to do “apt-get update” it worked fine, but there was annoying message like following:

# apt-get update
......
Fetched 5562B in 13s (421B/s)
Reading package lists... Done
W: There are no public key available for the following key IDs:
A70DAF536070D3A1
W: You may want to run apt-get update to correct these problems
#

UPDATE: Thanks to Kurt Fitzner we know, that:

There is already a mechanism to do this automatically:

$ apt-key update

This will obtain the necesary keys and import them. No need to go through gpg directly.

After …