![]() ![]() Most of them had to do with the network congestion between the primary and standby, which was causing high log file sync waits while LGWR was stuck on LNS waits (as the Data Guard had to run in Maximum Availability mode). The database in question (a 3-node Exadata RAC cluster, 11.2.0.4 database version, 18.1.4 Exadata storage software version, Active Data Guard to a remote standby with the same config) had been experiencing performance issues for months. Let me start by presenting some background for the problem. It was quite an interesting journey, with some twists and turns along the way. Call stack profiling and flame graphs have been a hot topic in Oracle tech blogs last few years, and recently I got a chance to use it to troubleshoot an actual production performance issue.
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