Adding a Storage Disk To Linux

Adding extra storage in Linux is one of those everyday sysadmin tasks — especially in virtual machines. In big enterprise setups, you’d normally use LVM (Logical Volume Management), but sometimes you just need to drop in a simple disk and make it usable.

That’s what we’ll do here: add a plain disk, partition it, format it, and mount it so Linux can use it.

Connect a New Disk

How you attach a disk depends on your setup:

• Physical server → crack open the case/rack and plug it in (not covered here).
• Virtual machine → add one through your hypervisor.

In this demo we’re using Virtual Machine Manager (a front-end for KVM/QEMU). The process is similar if you’re on VMware, VirtualBox, or Hyper-V.

Open the VM details, hit Add Hardware, and create a new disk:

We’ll add a couple of 10GiB virtual disks:

They’ll then show up as hardware for the VM:

Find the Added Disks with lsblk

Boot the VM, log in, become root, and run lsblk. You’ll see your new disks — the names depend on the hypervisor (sdb, vdb, etc.):

Here they’re vdb and vdc, which live in /dev/:

⚠️ Heads-up: storage management is root-level work. Don’t try this as a normal user.

Create a Partition Table with fdisk

Fresh disks are blank slates — no partition table, no use. - MBR = old style (limited, mostly legacy now). - GPT = modern, flexible, and what we’ll use.

Run fdisk on the new disk:

Inside fdisk: - g → create a GPT partition table - n → create a new Partition - p → print the partition table - m → print the help menu - w → write changes and exit

fdisk Help

Help inside fdisk can be found with m (some think of it as m for Menu)

Use fdisk to Create Partitions

Reopen fdisk on /dev/vdb and create a partition: - n → new partition - choose number, start, and size (or just hit Enter for defaults)

Here’s an example making a 1GiB partition:

Note

Pressing Enter at the prompts usually accepts sensible defaults

Validate Partition and Write to Disk

Still in fdisk: - p → print the partition table (double-check your work) - w → write to disk

Repeat these steps to create another partition on the disk that was created. Once both partitions are created, a simple lsblk should show both disks with partitions, ready for the next steps:

Make a File System On the Created Partitions

Partitions are just containers. To actually use them, format with a filesystem:

File System Types

Just for fun, we created two different types of file systems, one xfs and the other ext4. File system types are a big topic, but these are two very important types.

Create a Directory for the File Systems

In Linux, new storage doesn’t show up as a drive letter. You need to 'attach' it somewhere in the filesystem.

For this demo: - /app → XFS disk - /db → ext4 disk

Make Mount Points

sudo mkdir /app /db

As below (using root, therefore no sudo):

Make a Backup of /etc/fstab

The /etc/fstab file controls which filesystems get mounted at boot. It’s powerful but unforgiving: one bad entry can prevent the system from starting.

Make a backup first:

Make the Mounts Automatic and Permanent

Best practice is to mount by UUID (unique ID) instead of device name. Grab it with:

Get UUID of New Partition

blkid | grep vdb1 | awk ' { print $2 } '

Append it to /etc/fstab:

Append the UUID to fstab

blkid | grep vdb1 | awk ' { print $2 } ' >> /etc/fstab

Append, Don't Overwrite!

Note that this APPENDS (>>) to /etc/fstab. Do not overwrite /etc/fstab! (But if that happens, simply revert using the backup taken above!) It is highly recommended to confirm the output of the command is as expected BEFORE appending it to /etc/fstab. This kind of "trust but verify" mentality will save many blunders in the command-line.

Then check that /etc/fstab has this line:

Check fstab

UUID="<yourUUID>"     /app    xfs     defaults        0 0

In our example, /etc/fstab now looks like this:

Repeat for the other disk. The final /etc/fstab should look like this:

Mount & Validate the New Storage

Apply the changes with:

Mount All Filesystems in fstab

mount -a

Verify both disks are showing up and that there are no issues with:

Validate the New Mounts

mount | grep vd[bc] # will vary depending on setup/hypervisor
findmnt --verify

For example:

A couple other checks could be:

Test them by creating files, then reboot to make sure mounts survive.

If the system won’t boot, don’t panic — drop to root shell and restore your backup:

Restore fstab from Backup

cp /etc/fstab_bkup /etc/fstab

Go add some storage to a Linux system! Enjoy!

Using parted

As mentioned above, there is also a parted utility which works with storage disks.