We are running SUSE 12 SP3 which uses SSSD 1.13.4 which I believe is a LTM 
version.

Due to the large number of users and groups in our LDAP directory, and the 
limitations of some legacy Unix systems, we have some large groups that have 
been broken into "sub-groups" with the same GID but an incremental suffix. I 
don't believe this is an uncommon solution, and it has worked fine for many 
years. There are efforts underway to patch some older systems such that they 
can handle very large groups so that we can collapse these sub-groups, but it 
is a slow process and there are a lot of servers.

Recently we upgraded some Linux systems to SUSE 12 SP3 and this has made us 
transition to using SSSD instead of configuring LDAP in /etc/ldap/conf. In the 
last few weeks we have encountered an issue related to these groups with the 
same GID. Most of the time, everything works as before, and for instance 
"getent group" commands using either GID or (sub-group) name return results. 
However at times those commands return an empty list and the following error 
appears in the system log:

sssd[nss]: More groups have the same GID [nnnn] in directory server. SSSD will 
not work correctly.
(group ID elided in this email per company policy)

Using sss_cache to expire the entire cache, group cache or specific group from 
cache has no effect. I understand that this expires the entries, not removes 
them, but subsequent getent calls do not overwrite what was there, the error 
persists. Stopping SSSD, removing the cache DB and restarting was effective, 
but this is not a viable solution in production. Since the problem clears 
itself eventually (only to come back later) I tried various strategies, one of 
which was to do a "getent group" on every sub-group, and this does clear the 
problem (until it returns).

Since I discovered this issue on SUSE, others in the company have verified that 
it also appears in RH 6 and 7. RH 7 is running 1.16.0, so the problem is still 
present up to that release, though the above error message does not appear in 
the messages log. Instead there is an error in the sssd_nss.log:

[sssd[nss]] [cache_req_search_cache] (0x0020): CR #1122: Multiple objects were 
found when only one was expected!

Gareth

Gareth Beale (bemsid: 45600)
Enterprise High Performance Computing Service
Application Infrastructure Services
Global Information Technology Infrastrucure Services
Need help? http://iticket.web.boeing.com/secure/create.aspx?id=serverhpc / 
425-234-0911

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