[SSSD-users] sssd troubles under load

Lukas Slebodnik lslebodn at redhat.com
Thu Jan 22 20:05:40 UTC 2015


On (22/01/15 12:11), Orion Poplawski wrote:
>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?
Yes,
I have correlation in my mind between offline authentication and use case on
laptop and it is usual to reboot laptop.

To be precise offline authentication(pam) is not enabled by default
    @see man sssd.conf -> cache_credentials

LS


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