Cannot add data to Azure /dev/sdb1

I access my Azure VM on linux. Using df -kh, I can see my /dev/sdb1 temporary disk (https://i.sstatic.net/zKXmQ.png)

$ sudo -i blkid
...
/dev/sdb1: PARTUUID="7ec06285-01"
...

I want to use it to store data however, despite, googling and reading the Azure documentation, I did not find any way to add data to it.

cp test /dev/sdb1 cp: cannot create regular file '/dev/sdb1': Permission denied
sudo cp test /dev/sdb1 sudo: unable to resolve host HubertProduction: Temporary failure in name resolution
mkdir /dev/sdb1/TEST mkdir: cannot create directory ‘/dev/sdb1/TEST’: Not a directory

How can I use /dev/sdb1 to store data and access to them? It is mounted so do I need to format it? if so how?

All the post I found are about the fact this is a temp storage with no backup: I understand it and this is not the issue here.

Solution

I created one Linux Ubuntu VM and created one directory and mounted it on sdb1 temporary disk like below

Without sudo :-

mkdir /data2
mkdir: cannot create directory ‘/data2’: Permission denied

With sudo, It worked:-

sudo mkdir /data2

Mounted dir data2 on sdb1

sudo mount /dev/sdb1 /data2
cd /data2

Accessed data2

siliconuser@siliconvm:/data2$ lsblk

enter image description here

Now you can directly create files in /data2 and those files will be stored in the temporary disk sdb1

Refer below :-

enter image description here

You do not need to format the disk as it is already mounted on Azure Linux VM. But you can change its mounted directory from mnt to dir.

You can create the file by moving to /mnt directory where temporary disk sdb1 is mounted by default after vm creation without a need to mount sdb1 to another directory :-
Refer below :-

enter image description here

Its also showing DATALOSS_WARNING readme file which states that the files created under this directory will be deleted as this is a temporary disk.

Reference :-
https://amalgjose.com/2021/09/01/how-to-add-a-new-disk-to-a-linux-server-without-downtime-or-reboot/