dccm userdirs and "mailer"

Leandro Santi lesanti@uolsinectis.com.ar
Thu Jun 12 03:57:16 UTC 2003

On Wed, Jun 11, 2003, Spike Ilacqua wrote:
> ...
> "mailer" seems to always be "local" for anything but a forwarded
> address, so I could probably get away with using that.  However, I'm
> also thinking about hashing the userdirs.  On a big system you could
> potentially have thousands of user directoris, and that can bog down.
> I'm thinking of using the simple hash scheme some mailers use.  The user
> directories would go into subdirectories based on the first to letters
> of the account, i.e. "spike" -> "userdirs/s/p/spike".  Single letter
> accounts are handled by putting them in first directory for that letter
> i.e "a" -> "userdirs/a/a/a".
> Thoughts?

This hash function (ie userdirs/<fist>/<second>/) doesn't scale well.
For example you'll get lots of entries on, say, userdirs/j/o/johnsomething
or userdirs/s/m/smithsomething; but few on, say, userdirs/x/k/xksomething.

If you want somewhat better yet simple approach I'd suggest 
userdirs/<first>/<last> or userdirs/<first>/<second-to-last>/<last>/,
however this is still far from perfect. On really large systems its better 
to use a "real" hash function or change the underlying fs.


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