Checking Disk Read & Write Speed in Linux

We are going to use 2 tools for this, one is called hdparm to test read speed, and the second one is called dd, to test write speed.

First, install hdparm

$ sudo apt install hdparm -y

Then, get the disk name. The name of the disk in below example is /dev/sda.

$ lsblk

Test read speed using hdparm. -t option is to record the timing for the read process. In below example, the read speed is around 700MB/sec.

$ sudo hdparm -t /dev/sda

To test write speed, we will use dd command. dd will write a 1M file called speedtest.img to disk, and the "oflag=direct" option will make dd use direct IO, skipping any filesystem cache. dd will show the disk write speed after it finishes writing the file to disk. In below example, the write speed is 100MB/s.

$ dd if=/dev/zero of=speedtest.img bs=1M count=1 oflag=direct

Creating Partition Using cfdisk

Manipulating and partitioning hardisk can be a daunting task, especially for new sysadmin and if the disk has already contain data. Luckily, there is a tool that make this task easier, and that tool is called cfdisk.

First, we need to identify our disk name. This can be achieved by running lsblk

$ lsblk

Above is a sample output of lsblk. We can see that our disk name is sda (append /dev/ to the name for full path), and it has 130GB size. We can also see that only around 30GB has been used. We should have 100GB worth of free space for our new partition.

To start using cfdisk, just run it against the path of our disk, in this case /dev/sda

$ sudo cfdisk /dev/sda

We should be able to see this interface

Move the cursor using the down arrow key on our keyboard, so that the cursor lies on the 107374.19MB line

Make sure your cursor is at "New" button, and press Enter.

Choose "Primary" and press Enter.

We want to use the whole free space, so just leave the size as it is, and press Enter.

We now have a partition ready. To actually write the partition to the partition table, move your cursor using the right arrow key on the keyboard until it reached the "Write" button, and press Enter.

We will get  a warning message. Type "yes" and press Enter to confirm this action.

We will get this message once the partitioning is complete.

Quit cfdisk by choosing "Quit" and press Enter

Eventhough we have created the partition, but sometimes the partition table is not automatically updated. Run "partprobe" to inform the OS of the partition table change.

$ sudo partprobe

Use "lsblk" to see that the new partition has been created

$ lsblk