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Anyone who runs a DIY server or home NAS has found themselves in that panic situation at least once “from missing label”, staring four identical drives into the case and praying you don't take out the wrong one during a migration or failure.

If you have a mixed setup with a pool mergerfs, records of backup and units dedicated to video surveillance, Correctly identifying the physical device is essential. Here are the software tools to map your hardware before you pick up the screwdriver.

1. Tree view with lsblk

The command lsblk it is the starting point. It allows you to see the structure of the disks, mount points and filesystem labels.

lsblk -o NAME,SIZE,FSTYPE,LABEL,MOUNTPOINT,MODEL

Example output:

NAME   SIZE FSTYPE   LABEL            MOUNTPOINT  MODEL
sda    500G ext4     system           /           Samsung 870 EVO
sdb    4T   ext4     mergerfs_data1   /mnt/disk1  WDC WD40EFRX
sdc    4T   ext4     mergerfs_data2   /mnt/disk2  WDC WD40EFRX
sdd    2T   ext4     videosurv        /mnt/cam    ST2000VX008
    

In this example, thanks to the column LABEL and MODEL, we know right away that sdd it is the Seagate disk dedicated to cameras, while the others are the Western Digitals of the data pool.

2. The litmus test: smartctl and the Serial Number

If the disks are identical (same make and model), the only way to physically distinguish them is Serial number (S/N) printed on the label. smartctl (part of the package smartmontools) it is the definitive command.

sudo smartctl -i /dev/sdb

Look for the line relating to Serial Number:

Model Family:     Western Digital Red
Device Model:     WDC WD40EFRX-68N32N0
Serial Number:    WD-WCC7K1XXXXXX
    

3. Partition analysis with fdisk

If you need to understand how a disk is partitioned (for example to identify old remnants of a RAID or swap partitions), usa fdisk.

sudo fdisk -l /dev/sdb

This command will show you the “Disk identifier” and the exact list of partitions present (this is. Linux RAID autodetect o GPT).

4. Hardware map with lshw

While the previous commands focus on data, lshw he tells you “where” the disk is connected at the hardware bus level. This is very useful if you have additional SATA controllers.

sudo lshw -class disk -short

It will return you a table with the H/W path, allowing you to distinguish disks connected directly to the motherboard from those on PCI-Express cards or external enclosures.

My advice: Before proceeding with physical removal, always throws smartctl to get the serial number and write it on a post-it. Once you open the NAS, compare it with the disc label to be sure of the 100%.