[Samba] People with applications needing directories containing large numbers of files.

[Jeremy Allison]

I've been working (inspired by James Peach of SGI) on the
problem of using Samba3 with applications that need large
numbers of file (100,000 or more) per directory.

I think the current code in SVN in the SAMBA_3_0 branch
may hold the fix for this problem, so I'd like to request
people who need this functionality to give it a try.

The key was fixing the directory handling to read only
the current list requested instead of the old (up to 3.0.11)
behaviour of reading the entire directory into memory before
doling out names. Normally this would have broken OS/2
applications which have *very* strange delete semantics :-),
but by stealing logic from Samba4 (thanks tridge) I think
the current code in SVN handles this correctly.

So here's how to set up an application that needs large
number of files per directory in a way that doesn't damage
performance.

Firstly, you need to canonicalize all the files in the
directory to have one case, upper or lower - take your
pick (I chose upper as all my files were already upper
case names). Then set up a new custom share for the
application as follows :

[bigshare]
        path = /home/jeremy/tmp/manyfilesdir
        read only = no
        default case = upper
        preserve case = no
        short preserve case = no

Of course, use your own path and settings, but set the
case options to match the case of all the files in your
directory. The path should point at the large directory
needed for the application - any new files created in
there and in any paths under it will be forced by smbd
into upper case - but smbd will no longer have to scan
the directory for names - it knows that if a file doesn't
exist in upper case then it doesn't exist at all.

So please give this a test if you have problems with
Samba and large sized directories. Remember this is in SVN code
only, it isn't in the 3.0.11 pre releases or rc candidates,
as we need to ensure this new code is correct. If you
can help me test it it'll be in 3.0.12 (security problems
notwithstanding :-).

Cheers,

	Jeremy.