內存交換空間的構建
我們知道CPU計算與數據的存儲都會使用到內存，使用內存可以大大減少從磁盤讀取的時間，但是當物理內存不足時，就需要暫時將用不到的程序和數據挪到內存交換空間(swap)
作法：
1. 創建分區（fdisk ,文件）
2. 格式化為swap
3. 啟動
4. 查看
創建分區
舉例
[root@bogon ~]# fdisk /dev/sda
The number of cylinders for this disk is set to 2610.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Command (m for help): p
Disk /dev/sda: 21.4 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 1288 10241437+ 83 Linux
/dev/sda3 1289 1925 5116702+ 83 Linux
/dev/sda4 1926 2610 5502262+ 5 Extended
/dev/sda5 1926 2052 1020096 82 Linux swap / Solaris
/dev/sda6 2053 2115 506016 83 Linux
Command (m for help): t
Partition number (1-6): 6
Hex code (type L to list codes): 82
Changed system type of partition 6 to 82 (Linux swap / Solaris)
Command (m for help): p
Disk /dev/sda: 21.4 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 1288 10241437+ 83 Linux
/dev/sda3 1289 1925 5116702+ 83 Linux
/dev/sda4 1926 2610 5502262+ 5 Extended
/dev/sda5 1926 2052 1020096 82 Linux swap / Solaris
/dev/sda6 2053 2115 506016 82 Linux swap / Solaris
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 16: 設備或資源忙.
The kernel still uses the old table.
The new table will be used at the next reboot.
Syncing disks.
part[root@bogon ~]# partprobe
這裡需要在進行設置下system ID
格式化
語法：mkswap設備名稱
舉例
[root@bogon ~]# mkswap /dev/sda6
Setting up swapspace version 1, size = 518156 kB
啟動|關閉
語法：swapon [-s]設備名稱
swapoff設備名稱
選項與參數：
-s:查看所有swap文件系統
舉例1：啟動swap
[root@bogon ~]# swapon /dev/sda6
舉例2：查看所有swap
[root@bogon ~]# swapon -s
Filename Type Size Used Priority
/dev/sda5 partition 1020088 0 -1
/dev/sda6 partition 506008 0 -2
查看
語法：free
舉例
total used free shared buffers cached
Mem: 2074972 1380996 693976 0 106740 1000288
-/+ buffers/cache: 273968 1801004
Swap: 1526096 0 1526096
可以看到Swap空間增加1526096
