How to check disk health status in Linux

Monitoring disk health in Linux reduces the risk of sudden data loss by revealing failing HDDs and SSDs before they stop responding. Early detection allows storage to be replaced during maintenance windows instead of during outages, keeping services and personal files available.

Disk firmware exposes internal health metrics through S.M.A.R.T. (Self-Monitoring, Analysis, and Reporting Technology). On Linux these metrics are typically accessed with the smartctl utility from the smartmontools package, which can read attributes, run built-in self-tests, and show overall health summaries for devices such as /dev/sda or /dev/nvme0n1.

S.M.A.R.T. cannot detect every failure mode and does not substitute for regular backups, filesystem checks, or RAID monitoring. Some controllers or virtual disks may not expose full data, and intensive self-tests can temporarily impact performance on busy systems. The steps below focus on a short, non-destructive check on Ubuntu or other Debian-based distributions with root privileges available through sudo.

1. Open a terminal session on the Linux system.
2. Install the smartmontools package from the distribution repository.

   $ sudo apt update && sudo apt install --assume-yes smartmontools
   Hit:1 http://archive.ubuntu.com/ubuntu jammy InRelease
   Get:2 http://archive.ubuntu.com/ubuntu jammy-updates InRelease [119 kB]
   Get:3 http://archive.ubuntu.com/ubuntu jammy-security InRelease [110 kB]
   ##### snipped #####
   Reading package lists... Done
   Building dependency tree... Done
   Reading state information... Done
   The following NEW packages will be installed:
     smartmontools
   0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
   Need to get 546 kB of archives.
   After this operation, 1,893 kB of additional disk space will be used.
   Do you want to continue? [Y/n] y
   ##### snipped #####

   On Debian and Ubuntu, smartmontools provides the smartctl command; other distributions use package managers such as dnf, zypper, or pacman to install the same package.

3. List block devices to identify the target disk name.

   $ lsblk | grep -E 'disk|nvme'
   sda      8:0    0   20G  0 disk
   sdb      8:16   0    5G  0 disk
   nvme0n1 259:0   0  477G  0 disk

   This output shows classic SATA disks such as /dev/sda and /dev/sdb as well as an NVMe disk /dev/nvme0n1; the appropriate device name is required for later commands.

4. Query basic information on the selected disk to confirm that S.M.A.R.T. support is enabled.

   $ sudo smartctl -i /dev/sda
   smartctl 7.3 2022-02-28 r5338 [x86_64-linux-5.15.0-76-generic] (local build)
   Copyright (C) 2002-22, Bruce Allen, Christian Franke, www.smartmontools.org
   
   === START OF INFORMATION SECTION ===
   Model Family:     Samsung based SSDs
   Device Model:     Samsung SSD 870 EVO 1TB
   Serial Number:    S5RANX0T123456A
   LU WWN Device Id: 5 002538 f4a123456
   Firmware Version: SVT01B6Q
   User Capacity:    1,000,204,886,016 bytes [1.00 TB]
   SMART support is: Available - device has SMART capability.
   SMART support is: Enabled

   Proceed only when the output shows that S.M.A.R.T. support is available and enabled; some virtual disks or USB adapters may not expose these capabilities.

5. Start a short S.M.A.R.T. self-test on the selected disk.

   $ sudo smartctl -t short /dev/sda
   smartctl 7.1 2019-12-30 r5022 [x86_64-linux-5.4.0-47-generic] (local build)
   Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org
   
   
   === START OF OFFLINE IMMEDIATE AND SELF-TEST SECTION ===
   Sending command: "Execute SMART Short self-test routine immediately in off-line mode".
   Drive command "Execute SMART Short self-test routine immediately in off-line mode" successful.
   Testing has begun.
   Please wait 2 minutes for test to complete.
   Test will complete after Wed Jul 17 15:58:30 2019
   
   Use smartctl -X to abort test.

   Short self-tests are non-destructive but can still impact performance, so running tests on busy production disks may cause higher latency or temporary slowdowns.

6. Display the overall S.M.A.R.T. health status after the short test completes.

   $ sudo smartctl -H /dev/sda
   smartctl 7.1 2019-12-30 r5022 [x86_64-linux-5.4.0-47-generic] (local build)
   Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org
   
   === START OF READ SMART DATA SECTION ===
   SMART overall-health self-assessment test result: PASSED

   A result such as PASSED or OK indicates that the disk firmware does not currently consider the device to be failing, although backups remain essential.

7. Inspect detailed S.M.A.R.T. attributes to spot reallocated sectors or read errors.

   $ sudo smartctl -a /dev/sda
   ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
     5 Reallocated_Sector_Ct   0x0033   100   100   010    Pre-fail  Always       -       0
     9 Power_On_Hours          0x0032   098   098   000    Old_age   Always       -       1234
    12 Power_Cycle_Count       0x0032   099   099   000    Old_age   Always       -       57

   Growing counts for attributes such as Reallocated_Sector_Ct or Current_Pending_Sector often indicate impending failure even when the overall health status still shows PASSED.

8. Review the S.M.A.R.T. self-test log to confirm that recent tests completed without error.

   $ sudo smartctl -l selftest /dev/sda
   SMART Self-test log structure revision number 1
   Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
   # 1  Short offline       Completed without error       00%        1234         -

   A status of Completed without error for the most recent entry verifies that the short self-test finished successfully.