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

[Nikola Lečić]

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On Tue, 19 Feb 2008 10:21:18 -0500
Bill Moran <wmoran at potentialtech.com> wrote:
 
[...]
> > 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"
[...] 
> 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.

It seems that man pages (such as newfs(8) and tunefs(8)) don't have a
lot of details about this matter. OP can also read this very informative
post regarding disk fragmentation and time/space optimisation:

  http://lists.freebsd.org/pipermail/freebsd-stable/2007-April/034711.html

Regards.
- -- 
Nikola Lečić = Никола Лечић
fingerprint : FEF3 66AF C90E EDC3 D878  7CDC 956D F4AB A377 1C9B
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