Is fsck obsolet for journaling FS? - Was: How do I Automount [snip]

Oliver Grawert ogra at ubuntu.com
Sun Nov 29 18:46:36 UTC 2015


hi,
Am Sonntag, den 29.11.2015, 19:30 +0100 schrieb Ralf Mardorf:
> Hi,
> 
> On Sun, 29 Nov 2015 18:02:26 +0100, Oliver Grawert wrote:
> > > It still would be interesting to learn how fsck, recommended by
> > > the
> > > Ubuntu fstab help, is managed when using gnome-disks. Since I
> > > didn't
> > > see a screenshot that shows fsck settings, I suspect it
> > > automatically
> > > writes the value 2 to fstab, or how is it handled?  
> > dunno, try it out but effectively that field is legacy nonsense
> > anyway.
> > unless you use ext2 or minix disks without journalling ...

> Assumed journaling file systems don't require periodically fsck, than
> it
> shouldn't be per se recommended by Ubuntu help pages (and Wikis of
> other distros).
well, the docs are years old, feel free to find out what needs changing
and gain the knowlede on the go :) 


> Why does an Ubuntu default install sets the value for ext4 file
> systems
> to 1 for the root directory and to 2 for other ext4 directories?
> 
legacy reasons ... it wouldn't really be needed but the code in the
installer is there and works ...

> The only evidence I found on the quick, that fsck is obsolet for at
> least one purpose is:
> 
>   "A journaling file system is designed such that tools such as fsck
> do
>   not need to be run after unclean shutdown (i.e. crash)." -
>   https://en.wikipedia.org/wiki/Fsck
> 
>   "File system can become inconsistent due to several reasons and the
>   most common is abnormal shutdown due to hardware failure , power
>   failure or switching off the system without proper shutdown. Due to
>   these reasons the superblock in a file system is not updated and
> has
>   mismatched information relating to system data blocks, free blocks
> and
>   inodes ." -
>   http://www.adminschoice.com/repairing-unix-file-system-fsck

if you have worse probs than the ones a journal can solve the fs will
be remounted RO and should be inspected manually anyway ... and in teh
course of that you would use fsck to try to repair possible breakage
... for a normal boot you dont really need to run it (we had
discussions to only run it every n'th boot years ago but that was to
much effort to implement just to gain 0.5sec during boot)

also since this is relevant for the thread, please note that
technically /etc/fstab has not been necessary in years in ubuntu (try
it, move it away and reboot, your system will be fine and properly have
mounted all fileystems) 

ciao
	oli
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