[Samba] Is nss_winbind required?

[Alex Matthews]

Hi all,

Is it a necessity to use the winbind nss module?
I have run a few tests and having it enabled creates a massive 
bottleneck. It's not nss_winbind itself that is the bottleneck but 
something in the background (I'm guessing uid/rid->username code).
If I disable winbind in nsswitch.conf what impact will it have? Will the 
system continue to work?

eg:

#nss_winbind enabled on group and passwd
time samba-tool ntacl sysvolreset

real    3m58.240s
user    2m54.760s
sys     0m27.030s

#nss_winbind disabled
time samba-tool ntacl sysvolreset

real    0m46.940s
user    0m35.057s
sys     0m6.350s

#nss_winbind enabled on only group
time samba-tool ntacl sysvolreset

real    0m46.668s
user    0m34.790s
sys     0m6.263s

#nss_winbind enabled on only passwd
time samba-tool ntacl sysvolreset

real    4m7.639s
user    2m56.987s
sys     0m26.923s

#nss_winbind enabled on group and passwd with enum groups and users disabled
time samba-tool ntacl sysvolreset

real    4m1.464s
user    2m55.350s
sys     0m26.660s

#nss_winbind disabled and *nss-pam-ldap* enabled on passwd, shadow and group
time samba-tool ntacl sysvolreset

real    3m57.029s
user    3m0.913s
sys     0m30.570s



Please note this last test shows that it is not the nss_winbind module 
that it slow it is something 'behind the scenes'.
Also note that this is not just applicable to the sysvolreset (it was 
just a convenient method of testing). Copying a directory consisting of 
many small files (eg a windows roaming profile) can be excruciatingly 
slow! 50s+ for a 50mb folder!
I am sure that it is not a network or drive limitation, copying the 
folder locally and via NFS happen very quickly and copying the same 
folder from a standalone S3 install on the same hardware is 'fast' also.

Thanks,

Alex