performance problems in getsamfilepwuid() with netlogond

[Michael Glauche]

> Hi,
>
> Per the suggestions received on this list, I'm now running a SAMBA_TNG PDC
> concurrently with Samba 2.0.7 for filesharing.  For the most part, things
work
> pretty well, but I can't join a workstation to the domain because the
> connection to the PDC times out!
>
> The problem is that the smbpasswd file on the PDC is over 5000 lines long
> (we've been using 'encrypted passwords = yes' for some time now), and a
new
> workstation account is of course added at the bottom of the file.  I was
> astonished to find that netlogond calls getsamfilepwuid() on the
workstation
> account's uid... which causes the program to call getpwnam() for every
entry
> in the smbpasswd file until it reaches the one for the workstation!
Needless
> to say, this is a bit of a performance hit when using a flatfile password
> database.  If I shuffle entries around in the smbpasswd file to put the
> workstation accounts at the top, I can join the domain successfully; but
> obviously, there's no way to put /all/ of the smbpasswd entries at the
top.
>
> What are the chances that this function could be optimized?  The design is
> currently very clean, but it simply isn't scalable.  Would a patch be
accepted
> that rewrote this function, or would I be better off switching to a
different
> SAM backend?

I think the TDB impemenation can solve this issue.
from configure --help:
--with-sam-pwdb={passdb,tdb,nt5ldap}
                          which password-database to use (passdb)

Try it with pwdb=tdb

Beware that tdb password backend is not very much testet. (even
don't know if it should work ;)

One problem still exist (IIRC): samba looks up those users in the system
passwd file. There is an option " --with-surstdb     Use SURS tdb database",
but I guess its highly experimental ;)

regards,
   Michael