Handbook:Parts/Installation/Disks/fr

Les périphériques découpés en blocs
Nous allons étudier en profondeur les aspects de Gentoo qui concernent les disques, y compris les systèmes de fichiers de Linux, les partitions et les périphériques découpés en blocs. Une fois que les tenants et les aboutissants des disques et des systèmes de fichiers seront compris, nous configurerons les partitions et les systèmes de fichiers pour l'installation de Gentoo Linux.

Pour commencer,intéressons-nous aux périphériques découpés en blocs. Le plus connu des périphériques découpés en blocs est sans doute le premier disque sur un système Linux, à savoir. Les disques SCSI et Serial ATA sont tous les deux étiquetés ; même les disques IDE sont étiquetés avec la nouvelle structure de libata  dans le noyau. Avec l'ancienne structure des périphériques, le premier disque IDE est étiqueté.

Les périphériques découpés en blocs ci-dessus représentent une interface abstraite pour le disque. Les programmes utilisateurs peuvent utiliser ces périphériques découpés en blocs pour interagir avec votre disque sans se soucier de savoir s'il est IDE, SCSI ou quelque chose d'autre. Le programme peut simplement adresser le stockage sur le disque comme un groupe de blocs contigus de 512 octets, accessibles aléatoirement.

Introduction
Now that the partitions are created, it is time to place a filesystem on them. In the next section the various file systems that Linux supports are described. Readers that already know which filesystem to use can continue with Applying a filesystem to a partition. The others should read on to learn about the available filesystems...

Les systèmes de fichiers
Plusieurs systèmes de fichiers sont disponibles. Certains d'entre eux sont considérés stables sur  l'architecture, il est conseillé de lire sur les systèmes de fichiers et leur prise en charge avant d'en choisir un plus expérimental pour les partitions importantes.


 * btrfs
 * A next generation filesystem that provides many advanced features such as snapshotting, self-healing through checksums, transparent compression, subvolumes and integrated RAID. A few distributions have begun to ship it as an out-of-the-box option, but it is not production ready. Reports of filesystem corruption are common. Its developers urge people to run the latest kernel version for safety because the older ones have known problems. This has been the case for years and it is too early to tell if things have changed. Fixes for corruption issues are rarely backported to older kernels. Proceed with caution when using this filesystem!


 * ext2
 * This is the tried and true Linux filesystem but doesn't have metadata journaling, which means that routine ext2 filesystem checks at startup time can be quite time-consuming. There is now quite a selection of newer-generation journaled filesystems that can be checked for consistency very quickly and are thus generally preferred over their non-journaled counterparts. Journaled filesystems prevent long delays when the system is booted and the filesystem happens to be in an inconsistent state.


 * ext3
 * The journaled version of the ext2 filesystem, providing metadata journaling for fast recovery in addition to other enhanced journaling modes like full data and ordered data journaling. It uses an HTree index that enables high performance in almost all situations. In short, ext3 is a very good and reliable filesystem.


 * ext4
 * Initially created as a fork of ext3, ext4 brings new features, performance improvements, and removal of size limits with moderate changes to the on-disk format. It can span volumes up to 1 EB and with maximum file size of 16TB. Instead of the classic ext2/3 bitmap block allocation ext4 uses extents, which improve large file performance and reduce fragmentation. Ext4 also provides more sophisticated block allocation algorithms (delayed allocation and multiblock allocation) giving the filesystem driver more ways to optimize the layout of data on the disk. Ext4 is the recommended all-purpose all-platform filesystem.


 * f2fs
 * The Flash-Friendly File System was originally created by Samsung for the use with NAND flash memory. As of Q2, 2016, this filesystem is still considered immature, but it is a decent choice when installing Gentoo to microSD cards, USB drives, or other flash-based storage devices.


 * JFS
 * IBM's high-performance journaling filesystem. JFS is a light, fast and reliable B+tree-based filesystem with good performance in various conditions.


 * ReiserFS
 * A B+tree-based journaled filesystem that has good overall performance, especially when dealing with many tiny files at the cost of more CPU cycles. ReiserFS appears to be less maintained than other filesystems.


 * XFS
 * A filesystem with metadata journaling which comes with a robust feature-set and is optimized for scalability. XFS seems to be less forgiving to various hardware problems.


 * vfat
 * Also known as FAT32, is supported by Linux but does not support any permission settings. It is mostly used for interoperability with other operating systems (mainly Microsoft Windows) but is also a necessity for some system firmware (like UEFI).


 * NTFS
 * This "New Technology" filesystem is the flagship filesystem of Microsoft Windows. Similar to vfat above it does not store permission settings or extended attributes necessary for BSD or Linux to function properly, therefore it cannot be used as a root filesystem. It should only be used for interoperability with Windows systems (note the emphasis on only).

When using ext2, ext3, or ext4 on a small partition (less than 8GB), then the file system must be created with the proper options to reserve enough inodes. The  application uses the "bytes-per-inode" setting to calculate how many inodes a file system should have. On smaller partitions, it is advised to increase the calculated number of inodes.

Sur ext2, cela peut être fait à l'aide de la commande suivante:

Sur ext3 et ext4, ajouter l'option  pour activer la journalisation:

En général, ceci quadruple le nombre d' inodes pour un système de fichiers étant donné que son paramètre ''bytes-per-inode" passe de un tous les 16 ko à un tous les 4 ko. Cela peut être encore plus peaufiné en fournissant le rapport:

Appliquer un système de fichiers à une partition
To create a filesystem on a partition or volume, there are user space utilities available for each possible filesystem. Click the filesystem's name in the table below for additional information on each filesystem:

Par exemple, pour avoir la partition racine en ext4 tels que présenté dans  l'exemple de structure de partitions, il faut utiliser  les commandes suivantes:

Maintenant, vous pouvez créer les systèmes de fichiers sur les partitions – ou sur les volumes logiques – nouvellement créées.

Activating the swap partition
is the command that is used to initialize swap partitions:

To activate the swap partition, use :

Créer et activer la partition d'échange avec les commandes ci-dessus mentionnées.

Monter les partitions
Now that the partitions are initialized and are housing a filesystem, it is time to mount those partitions. Use the command, but don't forget to create the necessary mount directories for every partition created. As an example we mount the root partition:

Plus loin, dans les instructions, le système de fichiers / proc (une interface virtuelle avec le noyau) ainsi que d'autres pseudo-systèmes de fichiers du noyau seront montés. Mais d'abord, nous devons installer les fichiers d'installation de Gentoo.