Arch Linux

Komodo

Member

From: Oxford, UK

Registered: 2005-11-03

Posts: 674

umount -l vs umount -f

:?: Why is it that a forced unmount never works, whereas a lazy unmount always does? :?:

From what I can recall, forced unmount redirects I/O operations with badfs, right? And lazy unmount just unmounts your drive and cleans up all links to it later on.

But why does forced unmount never work? I can understand why lazy unmount works, since it ignores and bypasses any problems, and worries about them later...

Looking at the manpage for umount:

       -f     Force unmount (in case of an unreachable NFS system).  (Requires
              kernel 2.1.116 or later.)

       -l     Lazy unmount. Detach the filesystem from the filesystem  hierar-
              chy now, and cleanup all references to the filesystem as soon as
              it is not busy anymore.  (Requires kernel 2.4.11 or later.)

So am I to understand from this that umount -f is in fact only for one specific situation - where you have an unreachable NFS system?

Personally I've only mounted Server Message Block volumes, so I don't know how similar NFS is. Isn't it basically the linux version of SMB though?

Following on from this, I assume that the situation referred to in the manpage section quoted above would be where you've mounted an NFS system and the volume is then disconnected at its remote location?

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.oO Komodo Dave Oo.

Galdona

Member

Registered: 2006-03-15

Posts: 196

Re: umount -l vs umount -f

i was wondering the same thing

user

Member

Registered: 2006-03-29

Posts: 465

Re: umount -l vs umount -f

What are you trying to do?(WAYTTD)

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Gullible Jones

Member

Registered: 2004-12-29

Posts: 4,863

Re: umount -l vs umount -f

I think he might be trying to unmount a filesystem so he can fsck it.

jaboua

Member

Registered: 2005-11-05

Posts: 634

Re: umount -l vs umount -f

I've had the same problem several times - in the cases of a CD, loop filesystem or something being busy but I can't find out why. umount -f never worked for me either - so until recently I used to reboot, but then experimenting a bit I got it to unmount with -dilf options and used that since then - but it might be enough with just -l since it works for you...

_Gandalf_

Member

Registered: 2006-01-12

Posts: 735

Re: umount -l vs umount -f

I had many problems like this, Actually I don't store MP3/Movies/Video Clips on my laptop, they are all on an external HDD on the server where I mount it via NFS, sometimes my wireless router go crazy so the NFS is uinreachable... If this happens when I'm watching a movie, then I am way beyond screwed lol, coz I only used sync to mount it to prevent files be lost, this is good but not when the NFS goes off. I used to restart in this case, but sometimes umount -f/l works, most of the time it doesn't, I just reboot... kinda sucks, but it's ok it happens once/twice a year so it's ok

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