Creating a file for swap is much easier than creating a partition. We can use the “dd” command available in Linux to create a empty file and make that as swap. First check the available swap size using “free” like,
[root@localhost ~]# free
total used free shared buffers cached
Mem: 2042720 498204 1544516 0 33200 308624
-/+ buffers/cache: 156380 1886340
Swap: 3052268 0 3052268
So we have around 3GB as swap.
Let’s start by creating a empty file like,
[root@localhost ~]# dd if=/dev/zero of=/newswap bs=1024 count=128000
128000+0 records in
128000+0 records out
131072000 bytes (131 MB) copied, 0.661045 seconds, 198 MB/s
The “dd” command copies a amount of data block by block. In this
If=xx is the source. Read from file instead of standard input.
Of=yy is the target. Write to a file instead of standard output.
Bs=zz is both read and write and zz is bytes at a time.
So now the file is created, we need to set the file as swap using “mkswap” like
[root@localhost ~]# mkswap /newswap
Setting up swapspace version 1, size = 131067 kB
Now activate the swap using “swapon” like
[root@localhost ~]# swapon /newswap
Execute the “free” command to see how much swap is present now,
[root@localhost ~]# free
total used free shared buffers cached
Mem: 2042720 628076 1414644 0 33548 436620
-/+ buffers/cache: 157908 1884812
Swap: 3180260 0 3180260
Finally we need to add the line in the /etc/fstab like,
/newswap swap swap defaults 0 0
Save the file so this swap will automatically gets up during system initialization.
REMOVE SWAP FILE
For removing the Swap file ,just stop the swap using “swapoff” and then remove the file like,
[root@localhost ~]# swapoff -v /newswap
swapoff on /newswap
Finally remove the file using rm –r /newswap and also entry in the /etc/fstab file.
So by this we are now aware of swap partition and swap file.
More articles to come .Happy CodingJ
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