Quadratic fsck

[Nifty Fedora Mitch]

On Sun, Jul 27, 2008 at 06:51:47PM -0430, Patrick O'Callaghan wrote:
> On Sun, 2008-07-27 at 12:32 -0700, Chuck Forsberg WA7KGX N2469R wrote:
> > Forced fsck operations on huge filesystems (500GB) are
> > taking a very long time during bootup.  Some typical
> > situations:
> > 
> > /dev/sdb6            448936380 399105212  27026504  94% /w
> > /dev/sdc2            500028036 444954060  29674008  94% /v
> > /dev/sdc1            461404200 305735808 132230364  70% /y
> > 
> > How can I reduce this time?  Would converting these to ext4
> > speed up fsck?  Is converting to ext4 an option yet?
> > 
> >  Can something be done in the background
> > on a mounted file system to check it or at least minimize the
> > time it takes to run fsck on it?
> 
> Are you running fsck with every boot? In ext3 this is usually
> unnecessary. Most boots use the journal, which is very fast. I have a
> 500GB filesystem that's over 60% full, and is on an external USB disk so
> it's not particularly fast, but the check time is only a few seconds.
> 
> Use tune2fs to adjust the number of mounts to wait before using
> auto-fsck.
> 

How is the system halted.

If ya hit the power/reset button the .autofsck file at the root of
each will be found and a full fsck done.   It is also possible to have
fsck run in parallel on some file systems but the I/O hit may limit
the value of that.   It is also possible that all three were built at
the same time and as such are now being check at exactly the same time
each time....  Adjust the number of mounts count to be n, n+1, n+2... for the auto-fsck
to trigger on.  As long as the maximum is not insane this is a good
trick and it also helps N planned reboots later after a power failure
that would put them back in sync.



-- 
	T o m  M i t c h e l l 
	Looking for a place to hang my hat.