what is the meaning of "optimization changed from TIME to SPACE"

[Bill Moran]

In response to ivan dimitrov <dimitrovi58 at yahoo.com>:

> OK, but maybe this is not my case. I am using about 10% ...
> "/dev/md0       3.6M    318K    3.0M     9%    /storage/pub/www/ram"
> 
> But dmesg reports continuously:
> /storage/pub/www/ram: optimization changed from TIME to SPACE
> /storage/pub/www/ram: optimization changed from SPACE to TIME
> 
> about 10 times per sec.
> 
> so, how can i stop this optimization rock-and-roll?

You didn't mention that it was flipping back and forth before.

I expect that some program is creating files, then deleting them shortly
after, resulting in the partition filling up, switching to space opt,
then it's not full so it switches back to time opt.  However, unless
you look at the partition at exactly the right moment, you don't see
those files.  For example, was the optimization at space at the moment
you took that df?

You've got a 3.6M partition.  I could fill that up accidentally in less
than a second.  I stand by my original advice to add space.  Bump it
up to 16M or 32M and see if the problem goes away.

Alternately, if you're _really_ worried about what's taking up an
unexpected 3.0M of space, you could enable audit and track what
programs are creating files there.

> Bill Moran <wmoran at potentialtech.com> wrote: In response to Brian 
> :
> 
> > ivan dimitrov wrote:
> > > After upgrading from freebsd-5.5-R to 6.3-R, I get the following message in dmesg:
> > >
> > > "/storage/pub/www/ram: optimization changed from TIME to SPACE"
> > >
> > > I use a ram disk via the md driver.
> > > Here is the line from my fstab file:
> > >
> > > md      /storage/pub/www/ram    mfs     rw,-s4m                 2       0
> > >
> > > Does this mean that there is some sort of error? ...and is there anything that can be done, so that I don't get this message in dmesg?
> > >
> > > Any help will be greatly appreciated :)
> 
> UFS normally optimizes file placement for performance.  Unfortunately,
> in order to do this it has to write files in such a way that it
> sometimes wastes some space.  When the partition gets close to full,
> FreeBSD automatically switches to "space optimization" which doesn't
> waste any space, but doesn't perform as well.
> 
> The short answer is, "This is happening because your partition is too
> close to full.  It's not an error, but you should clean up some files
> or add space."
> 
> It also has nothing to do with the difference between 5.5 and 6.3.
> 
> -- 
> Bill Moran
> http://www.potentialtech.com
> _______________________________________________
> freebsd-questions at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-questions
> To unsubscribe, send any mail to "freebsd-questions-unsubscribe at freebsd.org"
> 
> 
>        
> ---------------------------------
> Be a better friend, newshound, and know-it-all with Yahoo! Mobile.  Try it now.
> _______________________________________________
> freebsd-questions at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-questions
> To unsubscribe, send any mail to "freebsd-questions-unsubscribe at freebsd.org"


-- 
Bill Moran
http://www.potentialtech.com