Create a swap partition under Linux

in centos6.8 System for columns , Creating swap partitions

view the swap partition of the current system

[Email protected] ~]# swapon-sfilenametypesizeused Priority/dev/sda3 partition20725720 -1

create /dev/sdb1 partition

[[email protected] ~]# fdisk -l /dev/sdbdisk  /dev/sdb: 214.7 gb, 214748364800 bytes255 heads, 63 sectors/track,  26108 cylindersunits = cylinders of 16065 * 512 = 8225280  bytesSector size  (logical/physical): 512 bytes / 512 bytesi/o  size  (Minimum/optimal): 512 bytes / 512 bytesdisk identifier:  0x420e5771    device boot      start          End      Blocks   Id   System/dev/sdb1                1         523     4200966    83  linux 

Format the partition :

[[email protected] ~]# mkswap/dev/sdb1setting up swapspace version 1, size = 4200960 kibno label, uuid=37ea704c-7fdd-4969 -a58d-19021c5a023a

to mount the swap partition manually :

[Email protected] ~]# swapon/dev/sdb1[[email protected] ~]# Swapon-sfilenametypesizeusedpriority/dev/sda3 PARTITION20725720-1/DEV/SDB1 partition42009600-2

writes mount option to /etc/fstab in

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Activate newly added swap partition in /etc/fstab

[Email protected] ~]# swapon-a

to view swap partitions within the system :

[[email protected] ~]# swapon - sfilenametypesizeusedpriority/dev/sda3                                 partition20725720  -1/dev/sdb1                                 partition42009600  -2 

However, there are priority levels for multiple swap partitions, in order of use, The higher priority is used by the system first. If you do not manually specify a priority When you mount it, each time you create a swap partition, the priority value is equal to the previous interchange partition priority value minus 1.

the user assigns a priority to the new swap partition, priority of 0 to 32767 must be specified

the benefits of assigning priorities, some swap partitions are stored on high-performance disks, and some are even on the outer tracks of the disk, these can improve the performance of the switching partition, in order for these high-performance switched partitions to execute first , the priority must be specified.

Create a partition /DEV/SDB2, Assuming the performance of this block is higher than the above two blocks.

[[EMAIL PROTECTED] ~]# FDISK -L /DEV/SDB DISK /DEV/SDB: 214.7 GB,  214748364800 bytes255 heads, 63 sectors/track, 26108 cylindersunits =  cylinders of 16065 * 512 = 8225280 bytesSector size  ( logical/physical): 512 bytes / 512 bytesi/o size  (minimum/optimal):  512 bytes / 512 bytesdisk identifier: 0x420e5771    device  boot      start         end       Blocks   Id  System/dev/sdb1                1          523     4200966   83  Linux/dev/sdb2              524        1046      4200997+  83  linux format [[Email protected] ~]# swapon  /DEV/SDB2 Write/etc/fstab

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re-read /etc/fstab to view the contents of the swap partition.

[Email protected] ~]# swapon-a[[email protected] ~]# Swapon-sfilenametypesizeusedpriority/dev/sda3                               PARTITION20725720-1/DEV/SDB1 PARTITION42009600-2/DEV/SDB2 partition42009920 1

/DEV/SDB2 priority is higher than /dev/sda3 and /dev/sdb1, using the swap partition takes precedence over /dev/sda2

There is also a problem : when the swap partition is already mounted, the Mount option is modified, or the size of the swap partition is changed, the swap-a can not be used to read when re-mounted Etc/fstab, the device that has been mounted, it is not automatically re-mounted. If you want to mount it again, you need to unmount the partition first and then use swapon-a to mount the partition again.

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re-read, priority hasn't been repaired.

[Email protected] ~]# swapon-a[[email protected] ~]# Swapon-sfilenametypesizeusedpriority/dev/sda3                               PARTITION20725720-1/DEV/SDB1 PARTITION42009600-2/DEV/SDB2 partition42009920 1

first uninstall, , the priority is changed.

[email protected] ~]# swapoff /dev/sdb1[[email  protected] ~]# swapon -a [[email protected] ~]# swapon - sfilenametypesizeusedpriority/dev/sda3                                 partition20725720  -1/dev/sdb1                                 partition42009600   2/dev/sdb2                                 partition42009920   1 

When you format a swap partition, you can specify the priority level

SWAP-P #/dev/sdb1 # Specifies the priority in the process of formatting Arabic numerals

Create a swap partition under Linux