Linux allows you to use part of your RAM as a block device, viewing it as a hard disk partition. The advantage of using a RAM disk is the extremely low latency (even when compared to SSDs). The disadvantage is that all contents will be lost after a reboot.
Before getting started, let's find out the file system that our root partition uses. Run the following command (T - print file system type, h - human readable):
$ df -Th
The result should look like this:
Filesystem Type Size Used Avail Use% Mounted on udev devtmpfs 1.1G 0 1.1G 0% /dev tmpfs tmpfs 214M 3.8M 210M 2% /run /dev/sda1 ext4 218G 4.1G 202G 2% / <- root partition tmpfs tmpfs 1.1G 252K 1.1G 1% /dev/shm tmpfs tmpfs 5.0M 4.0K 5.0M 1% /run/lock tmpfs tmpfs 1.1G 0 1.1G 0% /sys/fs/cgroup /dev/sda2 ext4 923M 73M 787M 9% /boot /dev/sda4 ext4 266G 62M 253G 1% /home
From the results, we will assume in the following commands that the file system is ext4. If it's not your case, just replace with what you have:
$ sudo mkdir /mnt/ramdisk $ sudo mount -t tmpfs -o size=1G ext4 /mnt/ramdisk
tmpfs /mnt/ramdisk tmpfs rw,nodev,nosuid,size=1G 0 0
That's it. We just created a 1Gb tmpfs ramdisk with an ext4 file system and mounted it at /mnt/ramdisk. Use df again to check this yourself.
As we mentioned before, you can't get I/O statistics regarding tmpfs since it is not a real partition. One solution to this problem is using pv to monitor the progress of data transfer through a pipe. This is a valid approach only if we consider the disk I/O being the bottleneck.
Next, we will generate 512Mb of random data and place it in /mnt/ramdisk/file first and then in /home/student/file. The transfer is done using dd with 2048-byte blocks.
$ pv /dev/urandom | dd of=/mnt/ramdisk/rand bs=2048 count=$((512 * 1024 * 1024 / 2048)) $ pv /dev/urandom | dd of=/home/student/rand bs=2048 count=$((512 * 1024 * 1024 / 2048))
Look at the elapsed time and average transfer speed. What conclusion can you draw?
Put one screenshot with the tmpfs partition in df output and one screenshot of both pv commands and write your conclusion.