[SSSD-users] SSSD with 389DS

Jakub Hrozek jhrozek at redhat.com
Thu Jan 16 11:06:37 UTC 2014


On Thu, Jan 16, 2014 at 11:29:53AM +0100, Mitja Mihelič wrote:
> Hi!
> 
> We are running a CentOS6 server using SSSD that connects to 389DS
> containing 70k user entries. Both servers are fully updated.
> SSSD and 389DS package versions:
> sssd-1.9.2-129.el6_5.4.x86_64
> 389-ds-base-1.2.11.15-31.el6_5.x86_64
> 
> Authoconfig was used to enable sssd.
>  authconfig --enablesssd --enablesssdauth
> --ldapbasedn=dc=users,dc=company,dc=tld --enableshadow
> --enablemkhomedir --enablelocauthorize --update
> PAM an NSS configs were updated as well.
> I have attached our sssd.conf.
> 
> The setup itself works allowing users to authenticate, but we are
> concerned about the performance.
> At first we tried with enumeration enabled, but there was a
> significant responsiveness drop during enumeration. A simple getent
> -s sss passwd USERNAME took more than 15 seconds. Result paging did
> not help.
> 
> Next we turned enumeration off and deleted the cache for a clean
> start. We tried simple getent requests with 1000 random usernames
> taken from a file. We ran the bash script consecutively a few times.
> The results:
> - run 1: 0m10.831s
> - run 2: 0m20.914s
> - run 3: 0m31.422s
> and so on. Each run took about 10 seconds more than the previous one.
> During the test sssd_be was using 100% of one core. During this time
> 389DS was practically idling. Its load (CPU, I/O) hardly showed any
> change.

Do you also see bad performance when the cache is not empty? (For
instance when many users log in in the morning when the day starts..)

> 
> What could be the reason for this performace issue?
> How would we best go about tuning this system?

One thing that might help would be fine-tuning the cache expiration, in
particular entry_cache_nowait_percentage. This midpoint refresh would
allow the SSSD to return data from cache right away while issuing an
update in the background.

Some users have also symlinked the cache to /dev/shm, but putting the
cache to ramdisk obviously removes it on reboot.


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