Handbook:Parts/Installation/Disks/ja

ブロックデバイス
Gentoo Linuxの、そしてLinux一般の、Linuxファイルシステム、パーティション、ブロックデバイスを含めた、ディスク中心の考え方について詳しく見てみましょう. ディスクの入出力とファイルシステムについて理解することで、Gentoo Linuxインストールのためのパーティションとファイルシステムを構築できるようになります.

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 newer libata framework in the kernel. When using the old device framework, then the first IDE drive is.

The block devices above represent an abstract interface to the disk. User programs can use these block devices to interact with your disk without worrying about whether the drives are IDE, SCSI, or something else. The program can simply address the storage on the disk as a bunch of contiguous, randomly-accessible 512-byte blocks.

はじめに
パーティションが作成できたら、その上にファイルシステムを作成しましょう. 次の節ではLinuxがサポートする各種ファイルシステムを紹介します. どのファイルシステムを使うかをすでに決めているなら、パーティションにファイルシステムを適用するへ進みましょう. そうでなければ、次の節を読んで利用可能なファイルシステムについて知るのがよいでしょう.

ファイルシステム
利用可能なファイルシステムは複数あります. そのうちいくつかはアーキテクチャ上で安定して動作するとされています--重要なパーティションに実験的なファイルシステムを選択するときは、事前にファイルシステムのサポート状況を十分に知っておくことを推奨します.


 * 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.

ext2では、これは次のコマンドで実行できます：

ext3とext4では、ジャーナリングを有効にするために オプションを追加しましょう：

上のコマンドは通常では、「inodeあたりのバイト数」を16kBから4kBに減らすので、ファイルシステムに4倍のinode数を確保できます. 比率を指定することで、さらに細かく調節することもできます：

パーティションにファイルシステムを適用する
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:

例えば、パーティション構造例の通りに、ルートパーティション（）をext4に設定するには、次のコマンドが使えます：

それでは、新しく作成したパーティション（または論理ボリューム）にファイルシステムを作成しましょう.

スワップパーティションを有効にする
はスワップパーティションを初期化するために使われるコマンドです：

スワップパーティションを有効化するには、を使います：

上述のコマンドで、スワップを作成して有効化しましょう.

マウント
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.