I don't use /dev/sdb and I can't delete it. In Azure->Disks i have only my Os_Disk 30GB, in VM tab in Disks there is also only Os_Disk.
fdisk -l shows 2 disks:
Disk /dev/sda: 30 GiB, 32212254720 bytes, 62914560 sectors
Disk model: Virtual Disk
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: ...
Device Start End Sectors Size Type
/dev/sda1 262144 62914526 62652383 29.9G Linux filesystem
/dev/sda14 2048 8191 6144 3M BIOS boot
/dev/sda15 8192 262143 253952 124M EFI System
Partition table entries are not in disk order.
Disk /dev/sdb: 20 GiB, 21474836480 bytes, 41943040 sectors
Disk model: Virtual Disk
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: ...
Device Boot Start End Sectors Size Id Type
/dev/sdb1 2048 41940991 41938944 20G 7 HPFS/NTFS/exFAT
My VM standard is A2_v2
I am completely new to azure, thanks for help
Azure A_v2-Series VMs have additional temporary disk attached(in your case it is /dev/sdb)
The temporary disk provides short-term storage for applications and processes, and is intended to only store data such as page or swap files.
Data on the temporary disk may be lost during a maintenance event, shutdown or when you redeploy a VM. During a successful standard reboot of the VM, data on the temporary disk will persist.
https://azure.microsoft.com/en-us/blog/new-av2-series-vm-sizes/
https://learn.microsoft.com/en-us/azure/virtual-machines/managed-disks-overview#temporary-disk