[Samba] winbind causing huge timeouts/delays since 4.8

[Ralph Böhme]

Am 24.02.2019 um 18:48 schrieb Rowland Penny via samba <samba at lists.samba.org>:
> On Sun, 24 Feb 2019 18:28:43 +0100 Ralph Böhme <slow at samba.org> wrote:
>> Am 24.02.2019 um 16:42 schrieb Rowland Penny via samba <samba at lists.samba.org>:
>>> On Sun, 24 Feb 2019 15:58:39 +0100 Ralph Böhme <slow at samba.org> wrote:
>>>> Another thing that a customer has just been bitten by, was a subtle
>>>> bug in winbindd's idmap cache that resulted in all xid2sid requests
>>>> going through the idmap backend, iow winbindd issued LDAP requests.
>>>> With a few thousand users, things came to a grinding halt.
>>>> 
>>>> https://bugzilla.samba.org/show_bug.cgi?id=13802
>>>> 
>>>> Patch just landed upstream.
>>> 
>>> That is the bug I was referring to and probably (amongst all the
>>> other cruft) what was causing the OP's problem.
>> 
>> Unlikely.
> 
> It is was I thought, but as the OP's setup is so convoluted, it is hard
> to say.

I don't think it's convoluted, it's certainly beyond the simple standard setup we all wish everybody was using, but I don't think it is broken as is. I just think an appropriate analysis requires more resources then is available on the list.

>>> However, this has nothing to
>>> do with using the 'ad' backend with Active Directory. We keep
>>> dancing around this problem, saying things like 'we need to fix
>>> this', we have been saying this since Samba 4 was released.
>> 
>> Which problem? Fix what? Been saying what?
> 
> There have been numerous discussions about the 'ad' backend over the
> years and they have all gone nowhere. The 'ad' backend still works in
> the same way as it did when Samba 4 was released and you still have to
> store the next uidNumber & gidNumber outside AD if you use the Samba
> tools.

Looks like you're mixing AD DC use case with member server use case. Can we please keep that seperate? Afaict, the one has nothing to do with the other.

>>> Windows Uses the SID-RID to identify the user and the domain it
>>> comes from, surely we can find a way to do this for Samba, we are
>>> half way there with the 'rid' backend.
>> 
>> I'm not really what "there" implies for you, but it seems
>> idmap_autorid is eventually the backend that takes you "there". :)
> 
> No it doesn't, at the moment, the only way to get the same ID on all
> Unix machines (this includes DC's) is to use the 'ad' backend.

Sure. But only certain use cases require the same id on all machines, many don't. I'm just saying that you should better not use idmap_ad, but instead use eg idmap_autorid unless you're setup requires idmap_ad.

> You think autorid is the way forward, well sorry, but in my opinion, it
> isn't.

Rowland, this is not about *the* way forward, this is about using the right backend at the right time.

-slow