How to Create Extra Large Dummy Files Quickly With Linux
Create a 1GB dummy file using the
dd command in your home directory.
dd if=/dev/random of=$HOME/dummy.data bs=1MB count=1024
The problem with the
dd command is it takes a considerable amount of time to create the file. Especially, if you are creating a large file with dozens of gigabytes it will take a considerable amount of time to write the file. For that kind of situation, we can use the
fallocate command. It will create a 10GB file within 1~2 seconds.
fallocate -l 10G dummy.data
fallocate command does not work on
Ext3 file systems.
In addition to the above examples, there is another way to create a large file in Linux using the
truncate command. This
truncate command is quite strange, it will create a 50GB file within 1~2 seconds, but surprisingly it will not take such a disk space. So we tried to create a whopping 15TB (Terabyte) file and it worked.
truncate -s 15T dummy.data