Mounting Azure LUN Drives or Data Disks in Ubuntu 24.04

I play in the “cloud,” and sometimes my cloud needs additional storage. Azure data disk or LUN storage is inexpensive and easy. Here is how I mounted my extra 128G disk in Ubuntu 24.04.

Find the disk

lsblk -o NAME,HCTL,SIZE,MOUNTPOINT | grep -i "sd"

Examples… sdc is my target.

kevin@cloud9:~$ lsblk -o NAME,HCTL,SIZE,MOUNTPOINT | grep -i "sd"
sda     0:0:0:0      64G
├─sda1               63G /
├─sda14               4M
├─sda15             106M /boot/efi
└─sda16             913M /boot
sdb     0:0:0:1      16G
└─sdb1               16G /mnt
sdc     1:0:0:0     128G

Format the disk and create the partitions

sudo fdisk /dev/sdc

Options

g
n
enter
enter
enter
w

kevin@cloud9:~$ sudo fdisk /dev/sdc

Welcome to fdisk (util-linux 2.39.3).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Device does not contain a recognized partition table.
Created a new DOS (MBR) disklabel with disk identifier 0x0d8af232.

Command (m for help): g
Created a new GPT disklabel (GUID: 8379B0DB-990C-452E-8764-46DDC2593BEE).

Command (m for help): n
Partition number (1-128, default 1):
First sector (2048-536870878, default 2048):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-536870878, default 536868863):

Created a new partition 1 of type 'Linux filesystem' and of size 256 GiB.

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

sudo mkfs.ext4 -F /dev/sdc1

kevin@cloud9:~$ sudo mkfs.ext4 -F /dev/sdc1
mke2fs 1.47.0 (5-Feb-2023)
Discarding device blocks: done
Creating filesystem with 67108352 4k blocks and 16777216 inodes
Filesystem UUID: 4ebca0b7-fb7e-45f8-8197-bf2b7a3e34f9
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000, 7962624, 11239424, 20480000, 23887872

Allocating group tables: done
Writing inode tables: done
Creating journal (262144 blocks):
done
Writing superblocks and filesystem accounting information: done

Mount drives

sudo mkdir -p /data

sudo mount /dev/sdc1 /data

Mount drive

I mount the drive and test fstab BEFORE I reboot. While recovering isn’t overly complicated, it is much easier to fix typos at this stage.

Warning

Do not use /mnt for your mount point. This is a temp disk in Azure and will be erased.

kevin@cloud9:~$ cat /mnt/
DATALOSS_WARNING_README.txt  data/                        lost+found/
kevin@cloud9:~$ cat /mnt/DATALOSS_WARNING_README.txt
WARNING: THIS IS A TEMPORARY DISK.

Any data stored on this drive is SUBJECT TO LOSS and THERE IS NO WAY TO
RECOVER IT.

Please do not use this disk for storing any personal or application data.

For additional details to please refer to the MSDN documentation at:
<http://msdn.microsoft.com/en-us/library/windowsazure/jj672979.aspx>

To remove this warning run:
    sudo chattr -i /mnt/DATALOSS_WARNING_README.txt
    sudo rm /mnt/DATALOSS_WARNING_README.txt

This warning is written each boot; to disable it:
    echo "manual" | sudo tee /etc/init/ephemeral-disk-warning.override
    sudo systemctl disable ephemeral-disk-warning.service

Create a mount point.

kevin@cloud9:~$ sudo mkdir -p /data

Mount the disk as a test.

kevin@cloud9:~$ sudo mount /dev/sdc1 /data

Verify everything is happy. You can see on the last line I have mounted sdc1 to /data

kevin@cloud9:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/root        29G  1.7G   27G   6% /
tmpfs           1.9G     0  1.9G   0% /dev/shm
tmpfs           773M  984K  772M   1% /run
tmpfs           5.0M     0  5.0M   0% /run/lock
efivarfs        128K   30K   94K  25% /sys/firmware/efi/efivars
/dev/sda16      881M   59M  761M   8% /boot
/dev/sda15      105M  6.1M   99M   6% /boot/efi
/dev/sdb1       7.8G   32K  7.4G   1% /mnt
tmpfs           387M   12K  387M   1% /run/user/1000
/dev/sdc1       124G   28K  123G   1% /data

Add drive to fstab

Next, we will make it so the drive auto mounts at the system start.

Find UUID

sudo blkid

kevin@cloud9:~$ sudo blkid
/dev/sdb1: UUID="dac9f2b8-e652-4c0c-8a3a-e89e72f99aab" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="e964e9fa-01"
/dev/sda16: LABEL="BOOT" UUID="a3459579-d08d-47d3-ba37-73b8f93832ea" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="db3c9060-8ad5-4d96-bce5-2ee8670b6b32"
/dev/sda15: LABEL_FATBOOT="UEFI" LABEL="UEFI" UUID="3D29-CB2F" BLOCK_SIZE="512" TYPE="vfat" PARTUUID="985e5b58-e1f3-4182-be08-8c79f0cbf260"
/dev/sda1: LABEL="cloudimg-rootfs" UUID="80e1e682-7307-4dc9-8dc4-a6af6afa284a" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="7766a12d-b53b-453f-a51f-d354e4fa13b1"
/dev/sdc1: UUID="4ebca0b7-fb7e-45f8-8197-bf2b7a3e34f9" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="82181696-640c-450f-83b7-9d9be3cc2401"
/dev/sda14: PARTUUID="e38bac6b-117c-4f40-b378-468801a61397"

Edit fstab

sudo vi /etc/fstab

Add a line similar to the following, adjusting for your system.

UUID=4ebca0b7-fb7e-45f8-8197-bf2b7a3e34f9 /data ext4 rw,relatime 0 0

kevin@cloud9:~$ sudo vi /etc/fstab
# CLOUD_IMG: This file was created/modified by the Cloud Image build process
UUID=80e1e682-7307-4dc9-8dc4-a6af6afa284a       /        ext4   discard,commit=30,errors=remount-ro     0 1
LABEL=BOOT      /boot   ext4    defaults,discard        0 2
UUID=3D29-CB2F  /boot/efi       vfat    umask=0077      0 1
UUID=4ebca0b7-fb7e-45f8-8197-bf2b7a3e34f9 /data ext4 rw,relatime 0 0
/dev/disk/cloud/azure_resource-part1    /mnt    auto    defaults,nofail,x-systemd.requires=cloud-init.service,_netdev,comment=cloudconfig       0       2

Unmount the drive so we can verify fstab is configured correctly.

sudo umount /dev/sdc1

kevin@cloud9:~$ sudo umount /dev/sdc1
kevin@cloud9:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/root        29G  1.7G   27G   6% /
tmpfs           1.9G     0  1.9G   0% /dev/shm
tmpfs           773M  984K  772M   1% /run
tmpfs           5.0M     0  5.0M   0% /run/lock
efivarfs        128K   30K   94K  25% /sys/firmware/efi/efivars
/dev/sda16      881M   59M  761M   8% /boot
/dev/sda15      105M  6.1M   99M   6% /boot/efi
/dev/sdb1       7.8G   32K  7.4G   1% /mnt
tmpfs           387M   12K  387M   1% /run/user/1000

Reload fstab and verify the drive mounted correctly.

sudo mount -av

kevin@cloud9:~$ sudo mount -av
/                        : ignored
/boot                    : already mounted
/boot/efi                : already mounted
/data                    : successfully mounted
/mnt                     : already mounted

If the system complains your fstab has been modified, run daemon-reload. daemon-reload will reload systemd files. You might need to run the mount command after the daemon-reload.

sudo systemctl daemon-reload

kevin@cloud9:~$ sudo systemctl daemon-reload
kevin@cloud9:~$ df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/root        61G  2.0G   60G   4% /
tmpfs           3.9G     0  3.9G   0% /dev/shm
tmpfs           1.6G 1012K  1.6G   1% /run
tmpfs           5.0M     0  5.0M   0% /run/lock
efivarfs        128K   35K   89K  29% /sys/firmware/efi/efivars
/dev/sda16      881M  107M  713M  13% /boot
/dev/sda15      105M  6.1M   99M   6% /boot/efi
/dev/sdb1        16G   28K   15G   1% /mnt
tmpfs           789M   12K  789M   1% /run/user/1000
/dev/sdc1       126G   24K  120G   1% /data

If you see your drive loaded, you should reboot the system to ensure fstab is working correctly. Nothing like rebooting a server 3 months later and having it not come up for a reason you forgot about.

Errors

The following error is due to data in your fstab not being correct. This is why we test before we reboot.

kevin@cloud9:~$ sudo mount -av
mount: /data: mount point does not exist.
       dmesg(1) may have more information after failed mount system call.

Thanks for stopping by!

ack quote: “You can throw a horse in water, but that is not how you get it to drink, either.”

Sources / Linkage

Attach a data disk to a Linux VM - Azure Virtual Machines | Microsoft Learn

Mounting Azure LUN Drives or Data Disks in Ubuntu 24.04

Find the disk

Format the disk and create the partitions

Mount drive

Add drive to fstab

Errors

Sources / Linkage

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