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How To Deal with Buffer I/O Errors on External HDDs When Unmounting

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In this article, we will discuss how to deal with Buffer I/O errors on external Hard Disk Drives (HDDs) when unmounting. These errors can be concerning, but with the right approach, you can effectively troubleshoot and resolve them.

Understanding Buffer I/O Errors

Buffer I/O errors typically occur when your system has trouble reading or writing to a block on the hard drive. When you unmount your external HDD, you might see messages in your logs such as “Buffer I/O error on device sdX, logical block XX.” These messages can indicate potential issues with the device, but to understand the severity of these errors, you need to gather more information.

Investigating Buffer I/O Errors

One of the first steps to investigate these errors is to run the fsck command on the partition(s) of the external HDD. The fsck command is used to check and optionally repair one or more Linux file systems. Here’s an example of how to use it:

fsck -a -y /dev/sda1

In this command, -a is an option that automatically repairs the file system without any user interaction, and -y gives automatic yes to prompts. Replace /dev/sda1 with your HDD partition. This command should be run from a live USB.

Using smartmontools

Another useful tool for assessing the health of your hard drive is the smartmontools package. This package contains two utility programs (smartctl and smartd) to control and monitor storage systems using the Self-Monitoring, Analysis, and Reporting Technology System (SMART) built into most modern ATA, SCSI, and NVMe disks.

You can install smartmontools using the following command:

sudo apt-get install smartmontools

Once installed, you can use the smartctl command to check the drive’s SMART status. Here’s how:

smartctl -a /dev/sda


smartctl -H /dev/sda

In these commands, -a prints all SMART information about the disk and -H assesses the health of the drive. Replace “sda” with your hard drive.

Running e2fsck

In some cases, running e2fsck -fv /dev/sdX can also be helpful. The e2fsck command is used to check a Linux ext2/ext3/ext4 file system. The -f option forces the check and -v gives verbose output. If this command runs without errors, it suggests that there might be another issue causing the buffer errors. However, if there are errors or mentions of moving sectors, it is recommended to back up your data immediately and prepare to replace the drive.


While buffer I/O errors can be concerning, they are not always indicative of a serious problem. However, without more information, it is difficult to determine the exact cause and severity of the errors. Monitoring the SMART status and running file system checks can provide valuable insights into the health of your external HDD. Always remember to back up your data regularly to prevent data loss.

What are some common causes of Buffer I/O errors on external HDDs?

Common causes of Buffer I/O errors on external HDDs can include physical damage to the hard drive, faulty cables or connectors, power issues, or software errors.

How can I check the health of my external HDD?

You can check the health of your external HDD by using tools like fsck, smartmontools, and e2fsck. These tools can help you diagnose any potential issues with your hard drive.

What should I do if I encounter Buffer I/O errors on my external HDD?

If you encounter Buffer I/O errors on your external HDD, you should first try running fsck to check and repair the file system. You can also use smartctl to assess the health of the drive. If errors persist or you notice any signs of physical damage, it is recommended to back up your data and consider replacing the drive.

Can Buffer I/O errors lead to data loss?

Buffer I/O errors can potentially lead to data loss if they indicate underlying issues with the hard drive. It is important to regularly back up your data to prevent any potential loss.

How often should I back up my data?

It is recommended to back up your data regularly, depending on how frequently you make changes or add new data. A good rule of thumb is to back up important data at least once a week or whenever significant changes are made.

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