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This article mainly introduces how to expand virtual memory under Linux, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let Xiaobian take you to understand.

When the physical memory is used up, and when the system needs more physical memory, the Inactive Pages in the physical memory is transferred to the Swap space. Swap space is a logical partition on the hard disk, so access is slower than physical memory. When the physical memory of the machine changes, the Swap partition should be expanded accordingly.

1. Check the size of the existing swap space

If you want to check the size of your existing virtual memory, use the command 'free-m'

[root@chenfancentos] # free-m total used free shared buffers cachedMem: 988 164823 026 48 Melody + buffers/cache: 90 898Swap: 1999 0 1999

According to the size of the existing swap space, choose the appropriate expansion size.

two。 Create a suitable swapfile

We can often use the "dd" command to create a file, use "if" to specify the source, basically can not write anything other than "/ dev/zero", and / dev/zero is a file unique to the UNIX system. "of" specifies the target file, "bs" defines the size of blocks, and "count" defines the number of blocks, the number of these two parameters determines the size of the target file.

[root@chenfancentos ~] # dd if=/dev/zero of=/tmp/swapfile bs=300M count=1 recorded 1'0 read in and 1'0 write out 314572800 bytes (315 MB) replicated, 13.9027 seconds, 22.6 MB/ seconds [root@chenfancentos ~] # du-h / tmp/swapfile300M / tmp/swapfile

You can see that a new swapfile file is generated with a size of 300m.

3. Format the swapfile [root@chenfancentos ~] # mkswap-f / tmp/swapfileSetting up swapspace version 1 you just created, size = 307196 KiBno label, UUID=c4e2a8b1-fa09-41ab-bcbf-63c273ed9598

You can see the successful UUID message after formatting

4. Realize automatic mounting of exchange files when booting

If we add the entry / tmp/swapfile swap swap defaults 00 to / etc/fstab, we will be able to boot and mount automatically.

[root@chenfancentos ~] # cat / etc/fstab# / etc/fstab# Created by anaconda on Sat Apr 2 19:37:01 2016 June # Accessible filesystems, by reference, are maintained under'/ dev/disk'# See man pages fstab (5), findfs (8) Mount (8) and/or blkid (8) for more info#UUID=301b2f9f-91d3-47dd-8a43-d377cba1cd5c / ext4 defaults 1 1UUID=812455f9-a63f-4b09-9336-05e3ada6f9a7 / boot ext4 defaults 1 2UUID=416480d0-662c-406c-a328-b4c2f370577b swap swap defaults 0 0tmpfs / dev/shm tmpfs defaults 0 0devpts / dev/pts devpts gid=5 Mode=620 0 0sysfs / sys sysfs defaults 0 0proc / proc proc defaults 0 0/tmp/swapfile swap swap defaults 0 0

In this way, even if it is restarted later, it can be mounted automatically.

5. Enable swapfile to view the virtual memory size [root@chenfancentos ~] # swapon / tmp/swapfile [root@chenfancentos ~] # free-m total used free shared buffers cachedMem: 988 136 852 0 10 50 Muhammad + buffers/cache: 74 913Swap: 2299 0 2299

It is exciting to see that compared to the initial virtual memory, there is now an increase of 300m.

Thank you for reading this article carefully. I hope the article "how to expand Virtual memory under Linux" shared by the editor will be helpful to everyone. At the same time, I also hope that you will support us and pay attention to the industry information channel. More related knowledge is waiting for you to learn!

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