Disk-Performace issue?

Michael Schuh michael.schuh at gmail.com
Tue May 10 05:37:36 PDT 2005

Hallo Charles,

thank you for this hint, but this is not the source....
i have this option as default in my kernels.

Iknow that putting tons of files in one directory is not really good for the
performance. I think also that the way get better by using subdirs.

But my problem ist that the performance fall from one moment to
another from 100% to ~10%........ this was not linear, ist was not a
ramp, it was the grand canion.... or the "Eiger Nordwand".  :-))

not that the performance at all is bad.

Thank you for your Hint


2005/5/10, Charles Swiger <cswiger at mac.com>:
> On May 10, 2005, at 6:46 AM, Michael Schuh wrote:
> > Now i have 2 Directories with ~500.000-600.000 files with an size of
> > ~5kByte.
> > by copying the files from one disk to another or an direktory on the
> > same disk
> > (equal behavior), i can see this behavior:
> > [ ... ]
> > Can anyone explain me from where this behavior can come?
> > Come thie eventually from the filesytem, or from my disks, so that
> > these are to hot? (I think not)
> Directories are kept as lists.  Adding files to the end of a list takes
> a longer time, as the list gets bigger.  There is a kernel option
> called DIRHASH (UFS_DIRHASH?) which can be enabled which will help this
> kind of situation out significantly, but even with it, you aren't going
> to get great performance when you put a half-million files into a
> single directory.
> Try breaking this content up into one or two levels of subdirectories.
> See the way the Squid cache works...
> --
> -Chuck

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