On 08/05/11 21:47, Patrick M. Hausen wrote:
Hi, all,
Am 05.08.2011 um 17:12 schrieb Christian Weisgerber:
Daniel Kalchev<dan...@digsys.bg> wrote:
On 02.08.11 12:46, Daniel O'Connor wrote:
I am pretty sure UFS does not have this problem. i.e. once you
delete/move the files out of the directory its performance would be
good again.
UFS would be the classic example of poor performance if you do this.
"Classic" indeed. UFS dirhash has pretty much taken care of this
a decade ago.
While dirhash is quite an improvement, it is definitely no silver bullet.
When I asked Kirk McKusick at last year's EuroBSDCon if having
a six-figure number of files in a single directory was a clever idea
(I just had a customer who ran into that situation), he just smiled
and shook his head.
The directory in question was the typo3temp/pics directory that
TYPO3 uses to scale images that are part of the website, so they
are handed to the browser in exactly the size they are supposed
to be rendered. The performance impact was quite heavy, because
at some point requests started to pile up, PHP scripts did not finish
in time, fcgi slots stayed used ... most of you will know that scenario.
At some threshold a machine goes from "loaded, maybe a bit slow,
but generally responsive" to "no f*ing way".
Best regards,
Patrick
I have similar situation here, but with a numerical simulation software,
which drops for each timestep of integration a file of all integrated
objects. Since the code is adopted and not very clever written in terms
of doinf its I/O, I have to deal with this. While performing dynamical
high resolution integrations of several hundreds of thousand objects
over a time scale of 1 Ga produces even with a larger dump-delta creates
a lot of files. making those files bigger results in a situation where
they are hard to analyse, so its a tradeoff situation.
ZFS and UFS2 perform bad on this situation, UFS2 even more than ZFS, but
also ZFS is still a pain in the ass.
Oliver
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