When the hard drives are physically identical it can be a little tricky. You can run commands such as lsblk, parted, and fdisk from the terminal to analyze the content and format of the drives.
Those commands takes parameters. This is a command I often use:
$ lsblk -o name,mountpoint,label,size,fstype,uuid | egrep -v "^loop"
NAME MOUNTPOINT LABEL SIZE FSTYPE UUID
├─sda1 Recovery 450M ntfs 4E98CBF598CBD99B
├─sda2 /boot/efi 100M vfat 90CE-9CE3
├─sda4 24.5G ntfs 3874F30874F2C820
├─sda5 [SWAP] 7.8G swap c9334080-5716-4af6-8223-c2f7ab8b42be
└─sda6 / 79G ext4 183a59f8-4023-4204-bf16-ef9ab0c61c7e
├─sdb1 1000M ext4 e6bf0b64-ef88-424e-9e2b-d8f397c009c8
└─sdb2 114.7G ext4 bd72b737-16e9-4c39-8b1e-610b8897a892
├─sdc2 /media/ljames/DFF1-8069 8.8G vfat DFF1-8069
├─sdc3 OS1 52.2G ext4 a13034ce-00a0-4bd2-8188-f780137413d7
├─sdc4 /media/ljames/verba1 verba1 44G ext4 248301e7-25c1-4fc6-8d98-6c96b5eaa284
└─sdc5 swap 9.8G swap a0fdc51f-79fd-4e77-a9f7-967384b56bc2
The columns for identifying how the disks are used are as follows:
- NAME - This is the name of the drive. The
sdX without a number is the whole physical drive. The number after the
sdX is the partition of the drive.
- MOUNTPOINT - This is where the drive is mounted. This is the information you can use in your case. As long as you see which drives have their mounting points, mounted, you can use that to identify which drives you currently have in use. The one with the mounted point
/ is mounted as root.
- LABEL - The label is a description that you provide. This is also convenient for you to identify how you are using the partitions of the drive.
- SIZE - Obviously the size of the partition.
- FSTYPE - The partition type can help you to identify which OS or other components of the way it's formatted.
- UUID - This is convenient information for having a unique identification for being sure which drive you have mounted.
The Boot Loader:
In the case of my example, the bootloader is in the
/dev/sda2 partition. A legacy bootloader is normally is located on reserved sectors of the drive. The bootloader can actually be on a USB drive or any other drive. The actual OS can be on a separate drive from the bootloader. It's most often on the same drive as the OS.
The is always the root, and identified by
/. FYI, it's possible to have symbolic links or actually separate links to partitions with the name of some of the OS folders, and having them mounted in the
So with this information, you can have a good idea of which drives or partitions to should be eliminated when formatting your drives, or any partitions of your drives.
By the way, I filtered out the loop devices to have a cleaner output. Recently there are many loop devices for Snap programs, which I already know have their data and installation files off the root (
/) partition. The filter removes reduncancy which I wouldn't consder the most important in this case.