4.Block layer

<meta http-equiv="CONTENT-TYPE" content="text/html; charset=utf-8"><title>1</title><meta name="GENERATOR" content="OpenOffice.org 2.0 (Linux)"><meta name="CREATED" content="20060406;19210000"><meta name="CHANGEDBY" content="zhao"><meta name="CHANGED" content="20060413;16230000"> <style> </style>

1. Block layer

   1. Support for Large Block Devices

Say Y here if you want to attach large (bigger than 2TB) discs to

your machine, or if you want to have a raid or loopback device

bigger than 2TB. Otherwise say N.

如果你想在你的计算机上安装大硬盘（大于2TB），或者大于2TB的磁盘阵列或备份设备，就选Y，否则选N。

1. IO Schedulers

1. Anticipatory I/O scheduler

The anticipatory I/O scheduler is the default disk scheduler. It is

generally a good choice for most environments, but is quite large and

complex when compared to the deadline I/O scheduler, it can also be

slower in some cases especially some database loads.

Anticipatory I/O scheduler是默认的磁盘调度程序，在大多数环境下他都是很好的选择，但与deadline I/O scheduler相比它很大很复杂，在加载某些数据库时尤其慢。

1. Deadline I/O scheduler

The deadline I/O scheduler is simple and compact, and is often as

good as the anticipatory I/O scheduler, and in some database

workloads, better. In the case of a single process performing I/O to

a disk at any one time, its behaviour is almost identical to the

anticipatory I/O scheduler and so is a good choice.

deadline I/O scheduler更简单紧凑，通常和Anticipatory I/O scheduler一样好，加载某些数据库是甚至更好，它是一个好的选择。

1. CFQ I/O scheduler

The CFQ I/O scheduler tries to distribute bandwidth equally

among all processes in the system. It should provide a fair

working environment, suitable for desktop systems.

CFQ I/O scheduler试图对系统的所有进程平均分配带宽，他提供一个公平的工作环境，适合桌面系统。

1. Default I/O scheduler

Select the I/O scheduler which will be used by default for all

block devices.

为所有的块设备选择默认的I/O调度程序。

1. Anticipatory

2. Deadline

3. CFQ

4. No-op