Creating a software RAID array on an already installed Ubuntu 11.04

Let's say you got confused by a misleading fake-RAID feature on an HP Blade server and you decided to ignore that the Ubuntu installer was telling you it found 2 disks while it was supposed (if it was actual hardware RAID) to be detecting only one. And let's say you are lucky to have 3 disks, and you only one to use two as the RAID array (and they do not contain your operating system, i.e. the / partition). You might wonder: "And now what? S**** you, HP!" (that last bit is if you left panic get you, of course).

Increasing battery working time on Lenovo W500

I'm a happy user of a Lenovo W500 but I had a very hard time getting anything more than 1h30 battery time, even with a brand new 9-cell battery (this one got me just 1h45 when using low screen brightness and minimum CPU). Then through a conversation with a friend and colleague, he suggested I disable the ATI graphics card and use the motherboard's... This means disabling it in the system's BIOS (not inside whatever operating system you use). Since I tried that, I get up to 4h45 on my 9-cell (with the minimum energy usage configuration in Ubuntu 10.10 64bit).

Memcache(d) to store PHP sessions

Edit: as of July 2014, there is a recent article discussing the use of php5-memcache instead of php5-memcache to store sessions on this blog. There are many posts around on the web about using memcached to store sessions data on high-availability servers, but few actually cover the whole topic and there are some elements that I thought might be of interest in the form of a quick recap. Memcached allows you to store frequently-used data in memory (RAM).

Debunking error (OS 10054) core_output_filter: writing data to the network

One of our customers has Apache logs (Xampp-based) full of this line:
[Tue Mar 02 16:21:41 2010] [info] [client] (OS 10054)Une connexion existante a dû être fermée par l'hôte distant.  : core_output_filter: writing data to the network
Sometimes (OS10053) is used as a variant, but the Apache error seems to be the same (core_output_filter: writing data to the network) Apparently, the error is widespread and only occurs on Windows operating system (that's where OS10054 error code comes from) and a few useful references for this are:
  • http://httpd.apac