Handbook:Parts/Installation/Disks/pt-br

Dispositivos de blocos
Vamos dar uma boa olhada nos aspectos relacionados a discos do Gentoo Linux e do Linux em geral, incluindo sistemas de arquivos Linux, partições e dispositivos de blocos. Uma vez que os detalhes de discos e partições estiverem compreendidos, configuraremos as partições e sistemas de arquivos para a instalação do Gentoo Linux.

Para começar, vamos dar uma olhada nos dispositivos de blocos. O dispositivo de bloco mais famoso é provavelmente aquele que representa o primeiro drive em um sistema Linux, o. Drives SCSI e Serial ATA são ambos chamados ; mesmo drives IDE são chamados pelo novo sistema libata no kernel. Se for usado o sistema antigo de dispositivos, então o primeiro drive IDE é chamado.

Os dispositivos de blocos acima representam uma interface abstrata para o disco. Programas de usuários podem usar esses dispositivos de blocos para interagir com seu disco sem se preocuparem se são IDE, SCSI ou de outro tipo. O programa pode simplesmente endereçar o armazenamento do disco como um grupo de blocos de 512 bytes contínuos e acessíveis aleatoriamente.

Introdução
Agora que as partições estão criadas, é hora de criar um sistema de arquivos nelas. Na próxima seção os diversos sistemas de arquivos suportados pelo Linux são descritos. Leitores que já souberem qual sistema de arquivos irão usar podem continuar em Criando um sistema de arquivos em uma partição.

Sistemas de arquivos
Several filesystems are available. Some of them are found stable on the architecture - it is advised to read up on the filesystems and their support state before selecting a more experimental one for important partitions.


 * 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 16 TB. 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.


 * 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).

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.

On ext2, this can be done using the following command:

On ext3 and ext4, add the  option to enable journaling:

This will generally quadruple the number of inodes for a given file system as its "bytes-per-inode" reduces from one every 16kB to one every 4kB. This can be tuned even further by providing the ratio:

Applying a filesystem to a partition
To create a filesystem on a partition or volume, there are tools available for each possible filesystem:

For instance, to have the root partition  in ext4 as used in the example partition structure, the following commands would be used:

Now create the filesystems on the newly created partitions (or logical volumes).

Activating the Swap Partition
is the command that is used to initialize swap partitions:

To activate the swap partition, use :

Create and activate the swap with the commands mentioned above.

Mounting
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:

Later in the instructions the proc filesystem (a virtual interface with the kernel) as well as other kernel psuedo-filesystems will be mounted. But first we install the Gentoo installation files.