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内存交换空间的构建

我们知道CPU计算与数据的存储都会使用到内存，使用内存可以大大减少从磁盘读取的时间，但是当物理内存不足时，就需要暂时将用不到的程序和数据挪到内存交换空间(swap)

作法：

1.       创建分区（fdisk ,文件）

2.       格式化为swap

3.       启动

4.       查看

创建分区

举例

[root@bogon ~]# fdisk /dev/sdaThe 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): pDisk /dev/sda: 21.4 GB, 21474836480 bytes255 heads, 63 sectors/track, 2610 cylindersUnits = 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  LinuxCommand (m for help): tPartition number (1-6): 6Hex code (type L to list codes): 82Changed system type of partition 6 to 82 (Linux swap / Solaris)Command (m for help): pDisk /dev/sda: 21.4 GB, 21474836480 bytes255 heads, 63 sectors/track, 2610 cylindersUnits = 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 / SolarisCommand (m for help): wThe partition table has been altered!Calling ioctl() to re-read partition table.WARNING: Re-reading the partition table failed with error 16: 设备或资源忙.The kernel still uses the old table.The new table will be used at the next reboot.Syncing disks.part[root@bogon ~]# partprobe

这里需要在进行设置下system ID

格式化

语法：mkswap设备名称

举例

[root@bogon ~]# mkswap /dev/sda6Setting up swapspace version 1, size = 518156 kB

启动|关闭

语法：swapon [-s]设备名称

swapoff设备名称

选项与参数：

-s:查看所有swap文件系统

举例1：启动swap

[root@bogon ~]# swapon /dev/sda6

举例2：查看所有swap

[root@bogon ~]# swapon -sFilename                                Type            Size    Used    Priority/dev/sda5                               partition       1020088 0       -1/dev/sda6                               partition       506008  0       -2

查看

语法：free

举例

total       used       free     shared    buffers     cachedMem:       2074972    1380996     693976          0     106740    1000288-/+ buffers/cache:     273968    1801004Swap:      1526096          0    1526096

可以看到Swap空间增加1526096

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