Linux Set swap (virtual memory area) __linux

[Root@gamedb ~]# Free–m

[Root@gamedb tmp]# dd If=/dev/zero of=/tmp/big_swap bs=1024 count=2000000

[Root@gamedb tmp]# Du-sh/tmp/big_swap

[Root@gamedb tmp]# Mkswap/tmp/big_swap

[Root@gamedb tmp]# Swapon/tmp/big_swap

[Root@gamedb tmp]# Free–m

[Root@gamedb tmp]# Vi/etc/fstab

# Label=swap-hda2 swap defaults 0 0

/tmp/big_swap Swap Defaults 0 0

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First, look at the memory and swap sizes and find that swap is half the size of memory

[Root@gamedb ~]# Free-m

Total used free shared buffers Cached

MEM:1001 338 662 0 8 307

-/+ buffers/cache:22 978

swap:509 0 509

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Second, decide to modify the swap size, first create a swap file for the partition at the appropriate place in space:

[Root@gamedb tmp]# dd If=/dev/zero of=/tmp/big_swap bs=1024 count=2000000

Read the 2000000+0 block.

Output 2000000+0 block.

(Note: If the infile,of represents a outfile,bs=1024 representation of the size of each block written is 1024b=1kb (1024B byte =1024*8bit bit)

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Third, to see whether the file size is created to meet the requirements:

[Root@gamedb tmp]# Du-sh Big_swap

2.0G Big_swap

[Root@gamedb tmp]# Ls-al Big_swap

-rw-r--r--1 root root 2048000000 June 11:55 big_swap

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Set the destination file as a swap file:

[Root@gamedb tmp]# Mkswap Big_swap

Setting up Swapspace version 1, size = 2047995 KB

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Activate swap to enable swap partition files immediately:

[Root@gamedb tmp]# Swapon Big_swap

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Vi. view memory and virtual memory again, and found that it has been modified normally:

[Root@gamedb tmp]# Free-m

Total used free shared buffers Cached

mem:1001 984 16 0 2 931

-/+ buffers/cache:50 950

swap:2462 0 2462

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If you want to enable it when you turn on, you need to modify the swap line in the file/etc/fstab:

[Root@gamedb tmp]# Vi/etc/fstab

# Label=swap-hda2 swap defaults 0 0

/tmp/big_swap Swap Defaults 0 0

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Attached: Fstab documents detailed:

The fstab contains important information about the partition, each of which is a partition record, each row can be divided into six parts, and the following is an example of/DEV/HDA7/EXT2 defaults 1 1:

1. The first item is the physical location of the storage unit you want to mount, such as HDB or/DEV/HDA6.

2. The second item is where you want to add it to the directory location, such as/home or/, which is actually the mount point that is prompted at installation time.

3. The third item is the so-called local filesystem, which includes the following formats: ext, ext2, MSDOS, iso9660, NFS, swap, or, for example, Ext2, can refer to the/prco/filesystems description.

4. The fourth item is the state you want to set when you mount, such as RO (read-only) or defaults (including other parameters such as RW, suid, exec, auto, Nouser, <