[SSSD-users] sssd troubles under load

Orion Poplawski orion at cora.nwra.com
Thu Jan 22 19:11:15 UTC 2015


On 01/22/2015 09:00 AM, Lukas Slebodnik wrote:
> On (21/01/15 11:22), Orion Poplawski wrote:
>> On 01/06/2015 05:06 PM, Orion Poplawski wrote:
>>> We're having some trouble with sssd on centos 7 under load on a VPS. 389ds
>>> ldap server for id/auth.  Part may be an issue with the VPS, but I'm trying to
>>> track down all possible issues.
>>>
>>> Also, we realized that we were running in a bit of a bad state - the primary
>>> ldap server was not available, but the backup was.
>>
>>> Trouble:
>>> (Tue Jan  6 22:30:31 2015) [sssd[be[default]]]
>>> [sss_ldap_init_sys_connect_done] (0x0020): sdap_async_sys_connect request failed.
>>> (Tue Jan  6 22:30:31 2015) [sssd[be[default]]] [sdap_sys_connect_done]
>>> (0x0020): sdap_async_connect_call request failed.
>>
>> I ended up filing https://fedorahosted.org/sssd/ticket/2562 as it seems like
>> sssd's handling of the ldap connection is not ideal.
>>
> I checked strace log file and I can confirm you are right.
> But I have no idea how to reproduce or fix it.
> Output from strace is not sufficient.
> 
> We would need to see sssd log files with high debug_level.
> You mentined the most problematic part of VPS is I/0.
> So increasing debug_level can just complicate situation.

I'll see what I can do.

> I can just give you an advice about *sync calls you mentioned in ticket.
> 
> It is not visible in strace log but fdatasync() and msync() are used on file
> descriptor of sssd cache (/var/lib/sss/db/cache_*.ldb. They are used in ldb/tdb
> for transactions.
> 
> If you do not need offline authentication you can mount tmpfs to directory
> /var/lib/sss/db/.
> 
> tmpfs   /var/lib/sss/db/ tmpfs size=300M,mode=0700,noauto,rootcontext=system_u:object_r:sssd_var_lib_t:s0 0 0

That is a good idea, thanks.  Offline auth should work though unless the
machine got rebooted, correct?


-- 
Orion Poplawski
Technical Manager                     303-415-9701 x222
NWRA, Boulder/CoRA Office             FAX: 303-415-9702
3380 Mitchell Lane                       orion at nwra.com
Boulder, CO 80301                   http://www.nwra.com


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