Device Mapper : une explication simple

Le Device Mapper (ou Carte/Correspondance des périphériques en français) permet de créer un périphérique block (un « disque dur »…) à partir d’autres périphériques blocks. 

En d’autres termes, dans l’utilisation la plus simple, vous pouvez utiliser  des morceaux de partitions de plusieurs disques, pour créer un disque composite.

C’est utilisé surtout avec le LVM et le RAID logiciel.

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Linux chage command and timers

The chage command in Linux is used to change the user password expiry information. Indeed, as the administrator, you can control at what frequency users have to change their password. It’s mainly dealing with timers and dates then.

The role of the different chage timers might not be clear for everyone though.

I found it simple to explain them with a timeline, centered around the life of the user password. Around this central timeline, you will find the actions required by the user and the administrator.

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File Descriptor : a simple explanation

What is a File Descriptor? Really, how does it work?

When you don’t have a clear and global comprehension of the Linux system, it’s hard to answer this question. Worse, when you search about File Descriptor on the net, the absolutely only things you’ll find will be either pages about redirections (as if the idea of File Descriptor could be reduced to standard input, output and error) or complicated stuff in C (you can feel my frustration here).

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Copy of VM : interfaces not appearing in Ubuntu

Coucou everyone!

In VMWare ESX (3.0 to 4.1i), you sometimes want to make a copy of an existing VM in production, for example to use the new one as a lab to developp new apps.

There are many ways to do that. The dirty one is simply to copy the VMDK+VMX files of the original VM to a new directory, then adding the VM to the ESX Inventory.

But you have to do it in the proper way for the Ethernet interface to be handled well.

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