How to Check Bad Sectors or Bad Blocks on Hard Disk in Linux

Let us start by defining a bad sector/block, it’s a section on a disk drive or flash memory that can not be read from or written to anymore, as a result of a fixed physical damage on the disk surface or failed flash memory transistors.

As bad sectors continue to accumulate, they can undesirably or destructively affect your disk drive or flash memory capacity or even lead to a possible hardware failure.

It is also important to note that the presence of bad blocks should alert you to start thinking of getting a new disk drive or simply mark the bad blocks as unusable.

Therefore, in this article, we will go through the necessary steps that can enable you determine the presence or absence of bad sectors on your Linux disk drive or flash memory using certain disk scanning utilities.

That said, below are the methods:

Check Bad Sectors in Linux Disks Using badblocks Tool

A badblocks program enables users to scan a device for bad sectors or blocks. The device can be a hard disk or an external disk drive, represented by a file such as /dev/sdc.

Firstly, use the fdisk command with superuser privileges to display information about all your disk drives or flash memory plus their partitions:

$ sudo fdisk -l
List Linux Filesystem Partitions
List Linux Filesystem Partitions

Then scan your Linux disk drive to check for bad sectors/blocks by typing:

$ sudo badblocks -v /dev/sda10 > badsectors.txt
Scan Hard Disk Bad Sectors in Linux
Scan Hard Disk Bad Sectors in Linux

In the command above, badblocks is scanning device /dev/sda10 (remember to specify your actual device) with the -v enabling it to display details of the operation. In addition, the results of the operation are stored in the file badsectors.txt by means of output redirection.

In case you discover any bad sectors on your disk drive, unmount the disk and instruct the operating system not to write to the reported sectors as follows.

You will need to employ e2fsck (for ext2/ext3/ext4 file systems) or fsck command with the badsectors.txt file and the device file as in the command below.

The -l option tells the command to add the block numbers listed in the file specified by filename (badsectors.txt) to the list of bad blocks.

------------ Specifically for ext2/ext3/ext4 file-systems ------------ 
$ sudo e2fsck -l badsectors.txt /dev/sda10

OR

------------ For other file-systems ------------ 
$ sudo fsck -l badsectors.txt /dev/sda10

Scan Bad Sectors on Linux Disk Using Smartmontools

This method is more reliable and efficient for modern disks (ATA/SATA and SCSI/SAS hard drives and solid-state drives) which ship in with a S.M.A.R.T (Self-Monitoring, Analysis and Reporting Technology) system that helps detect, report and possibly log their health status, so that you can figure out any impending hardware failures.

You can install smartmontools by running the command below:

------------ On Debian/Ubuntu based systems ------------ 
$ sudo apt-get install smartmontools

------------ On RHEL/CentOS based systems ------------ 
$ sudo yum install smartmontools

Once the installation is complete, use smartctl which controls the S.M.A.R.T system integrated into a disk. You can look through its man page or help page as follows:

$ man smartctl
$ smartctl -h

Now execute the smartctrl command and name your specific device as an argument as in the following command, the flag -H or --health is included to display the SMART overall health self-assessment test result.

$ sudo smartctl -H /dev/sda10
Check Linux Hard Disk Health
Check Linux Hard Disk Health

The result above indicates that your hard disk is healthy, and may not experience hardware failures any soon.

For an overview of disk information, use the -a or --all option to print out all SMART information concerning a disk and -x or --xall which displays all SMART and non-SMART information about a disk.

In this tutorial, we covered a very important topic concerning disk drive health diagnostics, you can reach us via the feedback section below to share your thoughts or ask any questions and remember to always stay connected to Tecmint.

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28 thoughts on “How to Check Bad Sectors or Bad Blocks on Hard Disk in Linux”

  1. I was doing this for a slightly impaired external drive, and it worked fine up until the actual call to fsck. Using your command verbatim,

    $ sudo e2fsck -l badsectors.txt /dev/sda1
    

    gave me a message that “fsck: the -l option can be used with one device only — ignore“; apparently because it was interpreting the text file as an additional device. However, thinking it over,

    # sudo fsck -t ntfs -l < ~/badsectors.txt /dev/sda1
    

    with an opening angle bracket before the file, in case it gets edited out) worked perfectly. I think you may have lost a symbol to HTML formatting there.

    Reply
  2. This wont work on large partitions (here is an example).

    # df
    Device           Start                    End               Sectors       Size     Type
    /dev/sda6    614612992 11618643967 11004030976  5.1T Linux filesystem
    
    # badblocks -v /dev/sda6 > badsectors_sda6.txt
    

    badblocks: Value too large for defined data type invalid end block (5502015488): must be 32-bit value

    Reply
  3. Whenever I try to start my pc, it shows like I/O buffer error, logical block error fsck exited with status code 8, Could this be a zero-length partition? I am completely new to it. So please help me I had some important documents in there. I don’t wanna format my hard drive as well. I would be really grateful if anyone could help me

    Reply

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