一、使用物理分区构建swap
1、先进行分区的行为。
1 [root@iZ255cppmtxZ ~]# fdisk /dev/xvdb 2 Welcome to fdisk (util-linux 2.23.2). 3 4 Changes will remain in memory only, until you decide to write them. 5 Be careful before using the write command. 6 7 8 Command (m for help): n 9 Partition type: 10 p primary (1 primary, 0 extended, 3 free) 11 e extended 12 Select (default p): p 13 Partition number (1,3,4, default 1): 4 14 First sector (20973568-62914559, default 20973568): 15 Using default value 20973568 16 Last sector, +sectors or +size{K,M,G} (20973568-62914559, default 62914559): +512M17 Partition 4 of type Linux and of size 10 GiB is set 18 19 Command (m for help): p 20 21 Disk /dev/xvdb: 32.2 GB, 32212254720 bytes, 62914560 sectors 22 Units = sectors of 1 * 512 = 512 bytes 23 Sector size (logical/physical): 512 bytes / 512 bytes 24 I/O size (minimum/optimal): 512 bytes / 512 bytes 25 Disk label type: dos 26 Disk identifier: 0x25a2caf5 27 28 Device Boot Start End Blocks Id System 29 /dev/xvdb2 2048 20973567 10485760 83 Linux 30 /dev/xvdb4 20973568 41945087 10485760 83 Linux 31 32 Command (m for help): t <==修改系统ID 33 Partition number (2,4, default 4): 4 34 Hex code (type L to list all codes): 82 <==改成swap的ID 35 Changed type of partition 'Linux' to 'Linux swap / Solaris' 36 37 Command (m for help): p 38 39 Disk /dev/xvdb: 32.2 GB, 32212254720 bytes, 62914560 sectors 40 Units = sectors of 1 * 512 = 512 bytes 41 Sector size (logical/physical): 512 bytes / 512 bytes 42 I/O size (minimum/optimal): 512 bytes / 512 bytes 43 Disk label type: dos 44 Disk identifier: 0x25a2caf5 45 46 Device Boot Start End Blocks Id System 47 /dev/xvdb2 2048 20973567 10485760 83 Linux 48 /dev/xvdb4 20973568 41945087 10485760 82 Linux swap / Solaris 49 50 Command (m for help): w 51 The partition table has been altered! 52 53 Calling ioctl() to re-read partition table. 54 Syncing disks.
强制内核更新分区表：
[root@iZ255cppmtxZ ~]# partprobe
2、开始构建swap格式。
[root@iZ255cppmtxZ ~]# mkswap /dev/xvdb4 Setting up swapspace version 1, size = 5485756 KiB no label, UUID=033a1d75-88fd-4347-8726-08d856cb9ad1
3、查实查看与加载。
1 [root@iZ255cppmtxZ ~]# swapon /dev/xvdb4 2 [root@iZ255cppmtxZ ~]# free 3 total used free shared buffers cached 4 Mem: 1016656 152956 863700 6624 11036 75828 5 -/+ buffers/cache: 66092 950564 6 Swap: 10485756 0 10485756
[root@iZ255cppmtxZ ~]# swapon -s Filename Type Size Used Priority /dev/xvdb4 partition 10485756 0 -1
二、使用文件系统构建swap
1、使用dd这个命令来新增一个128MB的文件在/data下面：
1 [root@iZ255cppmtxZ ~]# dd if=/dev/zero of=/data/swap bs=1M count=512 2 512+0 records in 3 512+0 records out 4 536870912 bytes (537 MB) copied, 7.82149 s, 68.6 MB/s
2、使用mkswap将/data/swap这个文件格式化为swap的文件格式：
1 [root@iZ255cppmtxZ ~]# mkswap /data/swap 2 Setting up swapspace version 1, size = 524284 KiB 3 no label, UUID=ede63d44-cf78-4d08-92ca-15fb38a625f4
3、使用swapon来将/data/swap启动
1 [root@iZ255cppmtxZ ~]# swapon /data/swap 2 swapon: /data/swap: insecure permissions 0644, 0600 suggested. 3 [root@iZ255cppmtxZ ~]# free -m 4 total used free shared buffers cached 5 Mem: 992 670 322 6 11 586 6 -/+ buffers/cache: 72 919 7 Swap: 511 0 511 8 [root@iZ255cppmtxZ ~]# swapon -s 9 Filename Type Size Used Priority 10 /data/swap file 524284 0 -1
使用swapoff关掉swapfile
1 [root@iZ255cppmtxZ ~]# swapoff /dev/xvdb4 2 [root@iZ255cppmtxZ ~]# swapoff /data/swap
为了能够让swap自动挂载，要修改/etc/fstab文件
在文件末尾加上
/data/swap swap swap default 0 0
这样就算重启系统，swap分区就不用手动挂载了。
