Posted by Riyaj Shamsudeen on December 31, 2009
I will be presenting on two topics in HOTSOS’ 2010, an Oracle performance focused conference, in my home town Dallas, Texas. You can read about my presentation topics in HOTSOS’ 2010 Riyaj . This symposium is a valued conference for performance engineers, DBAs and developers who are interested to know learn about performance. There are many great speakers presenting in this conference and the main page for this conference is HOTSOS ‘2010 . BTW, My friend Alex Gorbachev interviewed Gary Goodman and posted a video in his blog also.
Tanel Poder is conducting the HOTSOS training day this year. You can’t miss his training day and I heard that he is working on a MOTS (Mother Of all Tuning Script) and planning to release that in HOTSOS ‘2010.
On behalf of the Dallasites, I invite you to visit Dallas and attend this great conference.
I wish you a Happy and prosperous New Year ‘2010!
Posted in Performance tuning, Presentations | Tagged: hotsos, hotsos 2010, oracle performance | Leave a Comment »
Posted by Riyaj Shamsudeen on December 23, 2009
Global cache performance metrics are not correctly measured. It is not understood clearly either. There are even few blogs and web pages disseminating incorrect information. This blog entry is an attempt to offer few methods and scripts to understand global cache performance.
Always review all instances
It is very important to review the performance metrics from all instances in that RAC cluster, not just one instance that you are connected. If you have access to AWR reports, then it is critical to generate AWR reports (or statspack reports) from all instances. But, the problem is that, DBAs tend to generate AWR reports after logging in to each instance iteratively, enter couple of parameters and then reports are generated. Not exactly a convenient practice.
REM connect to each instance separately, type in the beginning snap_id and ending snap_id for each node etc..
There are few issues with this approach. It is a cumbersome practice if the instance count is higher. In addition to that, all of AWR reports are, in turn, accessing underlying AWR tables. Physically, rows from all instances are together in the same block and so, by executing these reports connecting to various instances, Global cache traffic is increased. If the database is suffering from Global cache (GC) performance issues then generating reports connecting to various instances is probably not a grand idea.
Posted in Oracle database internals, Performance tuning, RAC | Tagged: Average GC CR receive time, average gc CURRENT receive time, awrrpt.sql, gc cr block build time, gc cr block flush time, gc cr block receive time, oracle performance, RAC performance, RAC performance myths | 26 Comments »