[SSSD-users] sssd troubles under load

Lukas Slebodnik lslebodn at redhat.com
Thu Jan 22 16:00:34 UTC 2015


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 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

LS


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