How to check for disk error in Linux

Common disk errors are physical failures, bad sectors or blocks, and inconsistent filesystems. These disk errors can be checked using standard tools in Linux from the command line.

The disk must not be mounted when performing these tests. In the case where it's a root filesystem, and it's not possible to be unmounted when when there are logged-in users, you can use a live Linux system such as by booting into Ubuntu installer disk. It is similar to when recovering a lost partition table.

1. Launch terminal.
2. List available disks on your system.

   $ lsblk
   NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
   loop0    7:0    0 55.4M  1 loop /snap/core18/1997
   loop1    7:1    0  219M  1 loop /snap/gnome-3-34-1804/66
   loop2    7:2    0 64.8M  1 loop /snap/gtk-common-themes/1514
   loop3    7:3    0 32.3M  1 loop /snap/snapd/11588
   loop4    7:4    0   51M  1 loop /snap/snap-store/518
   loop5    7:5    0 65.1M  1 loop /snap/gtk-common-themes/1515
   sda      8:0    0   20G  0 disk 
   ├─sda1   8:1    0    1M  0 part 
   ├─sda2   8:2    0  513M  0 part /boot/efi
   └─sda3   8:3    0 19.5G  0 part /
   sdb      8:16   0   20G  0 disk /mnt/data
   sr0     11:0    1 1024M  0 rom

3. Make sure the disk you want to check is not mounted.

   $ sudo umount /dev/sdb
   [sudo] password for user:

4. Check disk S.M.A.R.T. health status using smarctl.

   $ sudo smartctl -H /dev/sdb
   smartctl 7.2 2020-12-30 r5155 [x86_64-linux-5.11.0-16-generic] (local build)
   Copyright (C) 2002-20, Bruce Allen, Christian Franke, www.smartmontools.org
   
   === START OF READ SMART DATA SECTION ===
   SMART Health Status: OK

   Related: How to check disk health status in Linux

5. Check for filesystem consistency of disk using fsck.

   $ sudo fsck /dev/sdb
   fsck from util-linux 2.36.1
   e2fsck 1.45.7 (28-Jan-2021)
   /dev/sdb: clean, 11/1310720 files, 126322/5242880 block

6. Check for disk bad blocks or bad sector using badblocks.

   $ sudo badblocks -v /dev/sdb
   Checking blocks 0 to 20971519
   Checking for bad blocks (read-only test): done                                                 
   Pass completed, 0 bad blocks found. (0/0/0 errors)