Hi, I work on software that formats and uses a disk on linux. When discovering the disks, we look for a non formatted disk with fdisk -l.

Ex:
If /dev/sda is formatted and /dev/sdb is not formatted, we use sdb.

For a server that's not on the cloud i have a question:

If we discover a scsi disk and a lun symlink to /dev/sdb, should we use that lun or the disk ?

I have noticed that many disks can be mapped to the same lun. This poses a problem.

https://unix.stackexchange.com/quest...-symbolic-link

Test somewhere in your code, if the file is a symlink or not, with:

Yeah, this shouldn't happen. What distribution are you using?

I work on azure VMs that have a scsi and 3 disks. But i'm trying to guess how it would be on premise outside the cloud.

Apparently this command show you the mappings. I found out that the last digit is the lun?

rgadmin@ubuntu22:~$ ls -ld /sys/block/sd*/device
lrwxrwxrwx 1 root root 0 Nov 30 11:23 /sys/block/sda/device -> ../../../0:0:0:0
lrwxrwxrwx 1 root root 0 Nov 30 11:24 /sys/block/sdb/device -> ../../../2:0:0:0
lrwxrwxrwx 1 root root 0 Nov 30 11:24 /sys/block/sdc/device -> ../../../2:0:0:1

So I see here that sda, sdb is on lun 0, sdc is on lun1.

Azure then has this file with symlinks. It excludes sda which is the disk that contains the OS.

rgadmin@ubuntu22:~$ ls -al /dev/disk/azure/scsi1
total 0
drwxr-xr-x 2 root root 60 Nov 30 11:46 .
drwxr-xr-x 3 root root 140 Nov 30 11:24 ..
lrwxrwxrwx 1 root root 12 Nov 30 11:46 lun0 -> ../../../sdb
lrwxrwxrwx 1 root root 12 Nov 30 11:46 lun1 -> ../../../sdc