Roughly how many users should Samba 4.0 be able to handle?

[Matthieu Patou]

On 01/17/2013 06:47 AM, Michael Wood wrote:
> Hi
>
> I'm trying to get an idea of how many users a Samba 4.0 server should be
> able to handle.
>
> In the past (one of the alphas) I tried adding about 40000 users and Samba
> slowed to a crawl.  I can't remember the details.  Just that I had to roll
> back to by last backup to fix the performance again.
So due to indexing 40 000 users will result into 200 000 ldb entries at 
least and I suspect 400 000 worst case.

I think it highly depend on the workload that you have.
If you have more than 1 DC it will be slow quite quickly because DCs 
keeps on asking each other for changes (I think it's every 15s but it's 
tuneable) and this kind of search is not indexed yet (we are doing 
something like '(usnchanged>=max_usn_from_last_replication)').
The good news is that I have a clear idea on how to implement indexing 
for this and this should start right after the first set of optimization 
are pushed.

If you have 1 DC and very selective query (ideal is just basedn query) 
then I don't think that doing tdb search in a 400 000 will be that bad 
but I will let tdb expert(s) give their pov but you are rarely in this 
case, and queries that looked selective (ie. 
base=MYOUWITH2USERS,DC=domain,DC=tld) are currently not so selective 
(but my patches are changing this).

I would love to do some tunning on big databases if someone can provide 
us a script to create a realistic big database (ie. not all users are 
called fooxxxx and not just 2 attributes are set) it will for sure help 
the process.

>
> I've compiled 4.0.1 and am busy adding 5000 users to my 1200 existing users
> (but on a test machine) to see what happens, but if anyone is running Samba
> 4.0 with large numbers of users I'd like to hear about it.
>
> Also, I know Matthieu's been working on optimising the ldb indexing code.
> Has that made it to master yet?
No but it's in process, feel free to try my ldb_perfs branch in my git 
repo to see.
>    And any other performance work since 4.0.0
> was released?
>
> Thanks.
>


-- 
Matthieu Patou
Samba Team
http://samba.org