How to check disk errors in Linux

Common disk errors include physical failures, bad sectors or blocks, and inconsistent filesystems, which can lead to various problems. Diagnosing these issues in Linux can be done using built-in command line tools.

The disk must not be mounted when performing these tests. If it's necessary to check the root filesystem and it cannot be unmounted due to logged-in users, you can boot into a live Linux system, such as the Ubuntu installer disk. This method is also helpful for recovering partition tables.

1. Open the terminal application.
2. Display the list of 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. Ensure the disk you wish to examine is unmounted.

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

4. Assess the disk's S.M.A.R.T. (Self-Monitoring, Analysis, and Reporting Technology) health status using smartctl.

   $ 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. Examine the filesystem consistency on the disk with 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. Inspect the disk for bad blocks or bad sectors 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)