Handbook:Parts/Installation/Disks/zh-cn

块设备
让我们来好好看看Gentoo Linux以及普通Linux中有关磁盘方面的知识，包括Linux文件系统，分区和块设备. 一旦磁盘和文件的来龙去脉都了解，我们将设置分区和文件系统的安装Gentoo Linux.

To begin, let's look at block devices. The most famous block device is probably the one that represents the first drive in a Linux system, namely. SCSI and Serial ATA drives are both labeled ; even IDE drives are labeled with the new libata framework in the kernel. When using the old device framework, then the first IDE drive is.

上面的块设备代表的抽象接口的磁盘. 用户程序可以使用这些块设备来与你的磁盘进行交互，而无需担心驱动器到底是IDE，SCSI还是其他什么东西. 该程序可以把磁盘当作一系列连续的，可随机访问的512字节块的存储.

介绍
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...

文件系统
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.


 * 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.


 * 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.