I've already mentioned on this blog very useful Consolidated Database Replay feature, for example while testing unified auditing performance impact (http://db-blog.web.cern.ch/blog/szymon-skorupinski/2014-06-unified-auditing-performance) or while investigating problems with hanging workload capture (http://db-b

 Topic: this post is about Linux perf and uprobes for tracing and profiling Oracle workloads for advanced troubleshooting.

Context

Topic: This post provides a short summary and pointers to previous work on Extended Stack Profiling for troubleshooting and performance investigations.

Topic: this post is about investigating Oracle wait events using stack profiles and flame graphs extended with OS-process state and Oracle wait event details.

Topic: This blog post is about kernel stack profiling and visualization with flame graphs.

Recently we were refreshing our recovery system infrastructure, by moving automatic recoveries to new servers, with big bunch of disks directly connected to each of them. Everything went fine until we started to run recoveries - they were much slower than before, even though they were running on more powerful hardware. We started investigation and found some misconfigurations, but after correcting them, performance gain was still too small.

A little bit scary title, isn't it? Please keep in mind that definitely it is neither supported nor advised method to solve your problems and you should be really careful while doing it - hopefully not on production environment. But it may sometimes happen that you end up with the situation where creating your own merge patch for Oracle database could not be as crazy idea as it sounds :).

Topic: this post is about some simple tools and techniques that can be used to drill down high-latency I/O events using SystemTap probes.

Topic: This post is about collecting and visualizing I/O latency histograms for NetApp filers in C-mode.

Regular readers of our blog probably already know that for most of our databases we're using two storage layers to keep our backups - NAS volumes as a primary layer and tapes as secondary one - please check "Datafile without backups - how to restore?" for more details. If you read another post "Importance of testing yours ba

The Case

Topic: event histogram metric, a script and some related discussions on collecting and displaying wait event latency histograms for Oracle performance troubleshooting.