Disabling atime

Ralf Corsepius rc040203 at freenet.de
Mon Aug 13 06:41:08 UTC 2007


On Sun, 2007-08-12 at 11:08 +0200, Nicolas Mailhot wrote:
> Le dimanche 12 août 2007 à 05:02 +0200, Ralf Corsepius a écrit :
> 
> > And how do you "fix" the "find"-based cron job users might have
> > implemented to clean up /var/cache from files not being used for time
> > span "x"?
> 
> Ralf,
> 
> Everyone can find pathological cases
Well, what you call pathological cases, I call "generalization".

That said, I consider notime to lack generality, because it violates
standards (POSIX), breaks applications and disables a feature of the OS.

> atime killed one of my flash cards before I learnt to disable it by
> default (nowadays the system is supposed to detect flash and disable
> atime, no idea how foolproof the check is)
May-be notime should be made the default on flash drives?

> atime is a legacy ass-backwards default
> That no one dared touching it so far does not make it less stupid
> We're making more user-impacting changes with less cause every release
> 
> Let's just disable atime asap so more testers check it before F8, and
> forget about it

As I already said many times before. It's trivial to implement
"atime-based find" scripts:

You'll hardly find any in a default installation, because they hardly
make much sense as part of a distro (exept. tmpwatch), but they make a
lot of sense as part of individual installation.

E.g.
* A cron job removing files not having been accessed for more than a
month in /var/cache/yum.
* Users wanting to remove "sound/data/image" files they have not
listened/read/looked at for time xxx inside of their /home
...

Similar stuff also can easily be integrated into applications. When
abandoning atime you'd break these applications and would force future
applications to administrate time-stamps as part of the application
instead of them being able to utilize the OSes resources.

> Let's just disable atime asap so more testers check it before F8, and
> forget about it

IMO, atime should be the default. Instead, users should learn to use
partitions (instead of lumping together everything into one partition
and to apply individual mount-flags to them, for those people thinking
notime is helpful to them - I don't find noatime helpful.

Ralf







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