Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I first noticed that fsck_hfs was running, taking up 50-75% of a CPU, yesterday. It continues to run today.

ps shows that it is doing /sbin/fsck_hfs -f -n -x -E /dev/disk3. Only problem: I don’t think I have a /dev/disk3.

  1. Why is it running?
  2. Will it ever finish?
    • Can I kill it?
  3. What is /dev/disk3? Could it be my Time Machine volume, which is not mounted at the moment?

System Info: MacBook Pro (2008). It has two disks installed—the internal disk (/dev/disk1) and a PC Card SSD (/dev/disk0, surprisingly). It connects to a remote Time Machine volume attached to an Airport Extreme base station.

share|improve this question
up vote 15 down vote accepted
  1. It was probably running from when your Time Machine volume was mounted.
  2. If the volume isn't present anymore, I doubt it.
    • I'm sure you can sudo killall fsck_hfs; it wouldn't hurt anything. (Have you tried restarting?)
  3. It probably is.
share|improve this answer
Thanks for the help! You were right. Moments after killing it, Time Machine popped up saying it was unable to verify my backup. It probably became confused last night when I closed my MacBook and took it home. Crazy that it will try to verify a ~750 GB disk image over Wi-Fi! I would have to leave my computer turned on and at the office for several days for it to complete… – Nate Jun 17 '10 at 19:30
You probably don't want to force quit it because it forces you to rebackup your entire computer and you then loose the existing back up history – Sirens Sep 1 '15 at 2:19
@Nate "… it will try to verify a ~750 GB disk image over Wi-Fi! …" – that's not what happens; only a fraction of the image is transmitted. Keyword: CopyHFSMeta, please see for example… – Graham Perrin Jan 30 at 12:04

Clicking on the Time Machine icon in the menu bar and choose "Skip verification" caused the fsck_hfs process to stop itself. Maybe a bit nicer than kill...

share|improve this answer

You can also click on the Time Machine icon, select "Open Time Machine Preferences...", and you should see a progress bar for how far along the "Backing Up" process is.

You can then click the "x" next to the progress bar to stop the verification process.

share|improve this answer

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .