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I'm getting this error when trying to repartition an external drive: "".

I want to run fsck -fy on the drive, but don't know the proper syntax for doing it on an external drive?

Can anyone help me out with this problem?

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2 Answers 2

Actually you want to do:

% sudo fsck_hfs -fy /dev/disk1s1 (depending on what partition you want to check).

It won't work with just fsck you have to put fsck_hfs as the command to run.

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I'm getting this error when trying to repartition an external drive: ""

That's a very descriptive error indeed.

In order to run fsck on an external drive, you first need to find out the identifier of the drive. Run diskutil list and check the name of the volume listed under IDENTIFIER – it'll be something like disk3s4, for example.

Use that name to run fsck. You can also pass the -f option to force checking a clean filesystem.

sudo fsck /dev/disk3s4

fsck has shorthands for diverse file system types:

  • fsck_hfs for HFS, use the -f option to force checking journaled systems
  • fsck_exfat for ExFAT (no -f option here)
  • fsck_msdos for FAT (no -f option here)
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Actually, it looks like as of 10.9, you can't use fsck without some sort of flag. Using the command as given here results in the help/usage output. –  ray Dec 15 '13 at 20:43
See Paul’s answer - you have to use fsck_hfs. –  Zev Eisenberg Feb 17 '14 at 21:46

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