How to wipe a signature from a disk device on Linux with wipefs command

I recently decommissioned Debian Linux based nas server and moved disk from my nas server to Linux-powered desktop. However, when I run fdisk command, I am getting the following error:
/dev/sdb: device contains a valid ‘LVM2_member’ signature; it is strongly recommended to wipe the device with wipefs(8) if this is unexpected, in order to avoid possible collisions
What is a wipefs and how do I use it on Linux?

Each disk and partition has some sort of signature and metadata/magic strings on it. The metadata used by operating system to configure disks or attach drivers and mount disks on your system. You can view such partition-table signatures/metadata/magic strings using the wipefs command. The same command can erase filesystem, raid or partition-table signatures/metadata.

Display or show current signatures

Type the following command:
$ sudo wipefs /dev/sda
OR
$ sudo wipefs /dev/sda1
Sample outputs:

Fig.01: Display current disk or partition signatures or magic strings

Be Careful: With just a few keystrokes, wipefs can wipe out part or all of your hard disk signature or working partition. Make sure you use correct device names with the wipefs command.

How do I erase current signatures from /dev/vdb?

The syntax is
$ sudo wipefs --all --force /dev/vdb
You can create a signature backup to the file $HOME/wipefs-{devname}-{offset}.bak:
$ sudo wipefs --all --force --backup /dev/vdb
Sample outputs:

/dev/vdb: 8 bytes were erased at offset 0x00000218 (LVM2_member): 4c 56 4d 32 20 30 30 31

Restores an ext2 signature from the backup file ~/wipefs-sdb-0x00000438.bak

You will also find a signature backup file with the following ls command:
$ sudo ls -l ~/wipefs-*.bak
Sample outputs:

-rw------- 1 root root 8 Feb 27 18:54 /root/wipefs-vdb-0x00000218.bak

To restore, run:
$ sudo dd if=~/wipefs-vdb-0x00000218.bak of=/dev/vdb seek=$((0x00000218)) bs=1 conv=notrunc
Sample outputs:

8+0 records in
8+0 records out
8 bytes copied, 0.00404186 s, 2.0 kB/s

Wiping the entire disk using dd command

You can also use the dd commandt o wipe out a signature from a disk device using the following syntax. The dd command works on Linux, FreeBSD, MacOS and Unix-like operating system. The syntax is:
$ sudo dd if=/dev/zero of=/dev/vdb bs=1M
Sample outputs:

4806672384 bytes (4.8 GB, 4.5 GiB) copied, 18.0002 s, 267 MB/s
dd: error writing '/dev/vdb': No space left on device
5121+0 records in
5120+0 records out
5368709120 bytes (5.4 GB, 5.0 GiB) copied, 18.5783 s, 289 MB/s

OR do secure erase with dd command showing progress bar:
$ sudo dd if=/dev/urandom of=/dev/vdb bs=1M status=progress
Sample outputs:

5348786176 bytes (5.3 GB, 5.0 GiB) copied, 249.005 s, 21.5 MB/s 
dd: error writing '/dev/vdb': No space left on device
5121+0 records in
5120+0 records out
5368709120 bytes (5.4 GB, 5.0 GiB) copied, 250.069 s, 21.5 MB/s

To wipe out just partitions:
$ sudo if=/dev/zero of=/dev/vdb1 bs=1M
To wipe out just the Master boot record (MBR), run:
$ sudo d if=/dev/zero of=/dev/vdb bs=446 count=1

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

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