I notice that when I unmount my external HDD I sometimes getting messages in my logs which saying:

Buffer I/O error on device sdX, logical block XX

Where the X stands for the device for example: sdc. How I seriously do I have to take these messages since the device only spewing this messages when I unmount it, when I mount and use it I don't get any messages and the device works fine at this point as far I can see.

Those messages can be normal -



to impending drive failure (unlikely).

smartmontools is required to determine the health of the drive and your drives passed.

smartctl -H /dev/sda
smartctl -a /dev/sda
smarrctl -t short /dev/sda

to show the results of tests

smartctl -l selftest /dev/sda


smartctl -l selftest /dev/sda ... Num Test_Description Status Remaining LifeTime(hours)


1 Short offline Completed without error 00% 1689 -

You can use fsck to check the file system, but fsck should be run from a live usb.

fsck -a -y /dev/sda1

the -a and -y options attempt repair.

with fsck you specify a partition.

See https://wiki.archlinux.org/index.php/S.M.A.R.T.



  • 1
    You can add -c and it will check for bad blocks as well – Geary Shull Nov 18 '14 at 13:40

Typically, this buffer issues can be indicative of a pending HDD failure. However, it is best to test the drive and verify and see where exactly the error lay. Please run e2fsck -fv /dev/sdX. If it runs without error, then there must be something else wrong. If it has any errors or mentions moving sectors, backup immediately and prepare to replace the drive. I recommend replacing it sooner rather than later in that case

  • 1
    Not necessarily ... they can be "just noise", we need more information. – Panther Nov 18 '14 at 2:11
  • Thus the command. Mind you, I have seen drives develop bad sectors and not fail, but these were always laptop drives under heavy use. – Geary Shull Nov 18 '14 at 2:12
  • smartmontools are better, IMO, then fsck to give hard drive health. – Panther Nov 18 '14 at 2:15
  • I do like smartmontools, since it is a little faster, but fsck is more thorough. – Geary Shull Nov 18 '14 at 2:41
  • 1
    fsck checks the file system rather then the hard drive. See lpic2.unix.nl/ch04s02.html or similar. – Panther Nov 18 '14 at 3:24

I formatted al my external hdd's to a EXT4 filesystem and I didn't see the errors again. Looks like it had something to do with the NTFS driver I guess.

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