Migrating Windows NT Environments to Linux

Bertil Starck best08 at handelsbanken.se
Fri Oct 10 21:32:32 GMT 2003


Anyone experienced the limitation of "NGROUPS_MAX 32" in the kernel  when 
running Samba/Winbind or solved the "Builtin Group Administrators" and the 
ACL considerations when migrating from WinNT to Linux?

Here follows our knowledge about the "NGROUPS_MAX 32" stuff and our 
aproach to migrate data with Robocopy. If there's someone having a better 
way to migrate, please speak up. 

- We have the PDC on the WinNT-side and we run into problem with the 
"NGROUPS_MAX 32" limit set in the kernel. Because of this a user that have 
more than 32 groups in his account will get the "access denied" msg and in 
the Linux log you will se this msg:
 "Oct  2 14:06:44 cslinux15 smbd[3981]:   Unable to initgroups. Error was Operation not permitted" 

The "man setgroups" will explain further about the NGROUPS_MAX limit.

-  Another consideration when migrating is the ACL. Samba/Winbind is not 
able to "see" the Builtin Groups in WinNT, and can because of that not set 
the ACL (setfacl) when e.g. the Administrators is the owner of a file. To 
try to solve this "Builtin"-problem we run a scripts before migrating data 
that changed any member in the Builtin group to a more useful name we used 
the ResourceKit command "subinacl".
 We try to use Robocopy for the data-transfer with this options "robocopy "j:" "f:\pilot\sthv0016\cdcs" /copy:datsou /mir /r:0 /ns /nc /nfl 
/ndl /log:f:\pilot\roblog_xxx.txt /tee", 
the mirror (mir) function in robocopy seems not to work when copying to 
Linux though.

- Another issue is the Local Group handling.

For our company it seems that the "NGROUPS_MAX 32" is a show stopper for 
the moment, maybe You will have any experience in this matter.

Best Regards Bertil Starck

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