I love visiting customers onsite. Last week I visited die Mobiliar in Bern, Switzerland. I received a list of open issues to discuss – which is very good to prepare a visit. And when we all were sitting together there was this “Ah, one final thing”. They have an issue with traces the databases writes every few seconds. As a remedy the DBAs increased the backup interval to remove the traces as otherwise the system would potentially run out of inodes or space. All the traces had the same pattern. And I learned quickly: these are MMON unconditional traces in Oracle 126.96.36.199.
MMON unconditional traces in Oracle 188.8.131.52
This happens sometimes. And it is not nice. A developer forgets either to remove a debug or trace event. Or the condition is not set correctly. Whatever is the case here, MMON (Manageability Monitor background process) writes an unconditional trace every 3 seconds. “Unconditional” means: it writes it every 3 seconds no matter what is happening.
AUTO SGA: kmgs_parameter_update_timeout gen0 0 mmon alive 1 AUTO SGA: kmgs_parameter_update_timeout gen0 0 mmon alive 1 dbkrfssm: mmon not open dbkrfssm: mmon not open *** 2017-08-16T16:38:23.916367+02:00 (CDB$ROOT(1)) AUTO SGA: kmgs_parameter_update_timeout gen0 0 mmon alive 1
This is known as
Bug 25415713 - MMON TRACE FILE GROWS WHEN NO TRACES ARE ENABLED. And the solution is to apply the patch for it.
As I was researching this for die Mobiliar I was wondering why such an issue – despite being known for over 6 months – is not included into any Update yet. After checking with the responsible Patching people somebody recognized that the patch was classified falsely as “non rolling installable” and therefore not considered for inclusion into Updates and Revisions. This got changed now and the fix should be included into the October 2018 Update. For July 2018 the code freeze unfortunately has been passed already.
In addition, the Note I had initially bookmarked, 2298766.1, has been archived or deleted. Instead this MOS Note has the details:
- MOS Note: 2319931.1
MMON trace file grows and is flooded with: kmgs_parameter_update_timeout Gen0 messages
- Die Mobiliar Blog: Why does my database generate so many traces?
- Patch 25415713
Update: May 24, 2018
As you can see in the COMMENTS sections, Ross mentioned that he received – different than Mobiliar – hugely growing traces instead many of them. The difference may be that Mobiliar is using Multitenant but I didn’t dig down deeply enough into it.