Oracle database internals by Riyaj

Discussions about Oracle performance tuning, RAC, Oracle internal & E-business suite.

Archive for the ‘RAC’ Category

OOUG RAC day presentation files and scripts

Posted by Riyaj Shamsudeen on November 18, 2015

Thanks for coming to my presentations in RAC day at Dublin, Ohio. Please find the presentation files below. Hopefully, I will get video files and upload that here too.

OOUG presentation files and scripts

md5 checksum of the zip file is:

$md5sum ooug_2015_pdf.zip
df8bdcbc02926e5bbd721514b473bf16  ooug_2015_pdf.zip

Posted in Oracle database internals, Performance tuning, Presentations, RAC | Tagged: , , | 1 Comment »

RAC day with Ohio Oracle User Group

Posted by Riyaj Shamsudeen on October 22, 2015

I will be talking about RAC and performance in-depth, with lots of demos, in a RAC day training with Ohio Oracle User group on Nov 16,2015 Monday. Venue for the presentation is Dublin, Ohio.

Agenda for the day:

08:00a – 09:00: Registration / Breakfast

09:00a – 09:15: Announcements -Introduction of the speaker

09:15a – 10:30: Underpinning for Oracle RAC and Clusterware

10:30a – 10:45: Break

10:45a – 11:45: RAC cache fusion internals

11:45a – 01:00: Lunch

01:00p – 02:00: RAC Performance tuning Part 1 – Wait events and object tuning

02:00p – 02:15: Break

02:15p – 03:30: RAC performance tuning Part 2 – locks, library cache locks etc.

03:30p – 03:45: Member Announcements, Gift Drawings

Please RSVP to the co-ordinators so that you will have a seat :)

OOUG RAC day

Posted in Oracle database internals, Performance tuning, Presentations, RAC | Tagged: , , , | 1 Comment »

IOUG Collaborate 2015

Posted by Riyaj Shamsudeen on March 25, 2015

I will be presenting two topics in IOUG Collaborate 2015 in Vegas. Use the show planner and add my presentations to your schedule :)

Session #189: April 13 Monday 9:15 to 10:15AM Topic: Oracle Database 12c In-Memory Internals. Room Palm B

Session #145: April 13 Monday 12:45PM-1:45PM Topic: Tools and Techniques for Advanced Debugging in Solaris & Linux (mostly live demo). Room Palm B.

Posted in inmemory, Oracle database internals, Performance tuning, Presentations, RAC | Tagged: , , , , , | Leave a Comment »

RMOUG Training Days 2015

Posted by Riyaj Shamsudeen on January 19, 2015

I will be talking in Rocky Mountain Oracle User Group Training Days 2015( http://www.rmoug.org), with live demos (hopefully there will be no failures in the demo). My topics are:

Feb 17: Deep dive: 3:15PM to 5:15PM – RAC 12c optimization: I will discuss RAC global cache layer in detail with a few demos. You probably can’t find these deep Global Cache layer details anywhere else :)

Feb 19: Wednesday: 2:45PM to 3:45PM – Advanced UNIX tools: I will discuss both Solaris and Linux advanced tools to debug deep performance issues.

Feb 19: Wednesday: 12:15PM – 1:15PM – Exadata SIG panel with Alex Fatkulin.

Come to Denver. Come on, it won’t be cold ( I think :) )

Uploading presentation and scripts of the presentation files: RMOUG_2015_Riyaj_RAC_12c_optim files

Presentation files for Unix tools demos: RMOUG_2015_Riyaj_Unix_tools

Posted in 11g, 12c, Presentations, RAC | Tagged: , , , | 1 Comment »

Golden rules of RAC performance diagnostics

Posted by Riyaj Shamsudeen on March 20, 2014

After collaborating with many performance engineers in a RAC database, I have come to realize that there are common pattern among the (mis)diagnosis. This blog about discussing those issues. I talked about this in Hotsos 2014 conference also.

Golden rules

Here are the golden rules of RAC performance diagnostics. These rules may not apply general RAC configuration issues though.

  1. Beware of top event tunnel vision
  2. Eliminate infrastructure as an issue
  3. Identify problem-inducing instance
  4. Review send-side metrics also
  5. Use histograms, not just averages

Looks like, this may be better read as a document. So, please use the pdf files of the presentation and a paper. Presentation slide #10 shows indepth coverage on gc buffer busy* wait events. I will try to blog about that slide later (hopefully).

Golden rules of RAC diagnostics paper

Golden rules of rac diagnostics ppt

Scripts mentioned in the presentation can be downloaded here.

scripts

Posted in 11g, Performance tuning, Presentations, RAC | Tagged: , , , , , | 3 Comments »

Dynamic Resource Mastering in 12c

Posted by Riyaj Shamsudeen on February 28, 2014

I blogged about Dynamic Resource Mastering (DRM) in RAC here . DRM freezes the global resources during the reconfiguration event and no new resources can be allocated during the reconfiguration. This freeze has a dramatic effect of inducing huge amount of waits for gc buffer busy [acquire|release] events and other gcs drm freeze release, gcs remaster events. In database version 12c, DRM has been improved further.

A major improvement I see is that not all resources are frozen at any time. Essentially, resources are broken down in to partitions and only a resource partition is frozen. This improvement should decrease the impact of DRM related waits tremendously.

LMON Trace file

Following shows the snippet from the LMON trace file. As you see, only one resource partition is frozen, at-a-time. Resources in the first partition is frozen, completes the resource remastering tasks, and unfreezes that resource partition. Then freezes next resource partition and continues until all resources are remastered.

Read the rest of this entry »

Posted in 12c, Performance tuning, RAC | Tagged: , , , | Leave a Comment »

Hotsos 2014

Posted by Riyaj Shamsudeen on February 25, 2014

I will be presenting in HOTSOS symposium 2014 discussing correct methods to diagnose RAC performance issues. Very surprisingly, even very senior performance engineers make mistakes in their analysis while reviewing RAC issues. Come to my presentation and learn the golden rules of RAC performance diagnostics.

Posted in 12c, Performance tuning, Presentations, RAC | Leave a Comment »

Scripts to create AWR reports quickly.

Posted by Riyaj Shamsudeen on November 12, 2013

It is easier to create one or two AWR reports quickly using OEM. But, what if you have to create AWR reports for many snapshots? For example, your Oracle support analyst wants you to supply 10 1-hour AWR reports from 10AM to 8PM in a 8 node cluster? That’s about 80 AWR reports to create! Okay, okay, I may(!) be overselling it, but you get the point. It is useful to have a script to create AWR report for all instances for a given range of snapshot IDs. Following scripts are handy:

1. To create one AWR report per instance, for the last snap duration : awrrpt_all_gen.sql
2. Same as (1) but in html format : awrrpt_all_genhtml.sql
3. To create one AWR report per instance, for a range of snap IDs : awrrpt_all_range_gen.sql
4. To create one AWR report, per instance, per snap ID : awrrpt_all_multi_gen.sql

Zip file: awrrpt_scripts

These scripts do not modify anything in the database, just retrieves the data using dbms_workload_repository package. Test the scripts to understand further. Of course, you need access to dbms_workload_repository and access to gv$instance.

Posted in Oracle database internals, Performance tuning, RAC | Tagged: , , , | 8 Comments »

Oaktable world presentation

Posted by Riyaj Shamsudeen on September 18, 2013

I will be hacking RAC internals with few LINUX tools in Oaktable world presentation series, in SFO. Details are available at Oaktable World 2013

Hope to see you there!

Posted in Oracle database internals, RAC | Tagged: | Leave a Comment »

RAC Internals: cached sequences and 12c

Posted by Riyaj Shamsudeen on September 9, 2013

Introduction

I blogged about DFS lock handle contention in an earlier blog entry. SV resources in Global Resource Directory (GRD) is used to maintain the cached sequence values. I will further probe the internal mechanics involved in the cached sequences. I will also discuss minor changes in the resource names to support pluggable databases (version 12c).

SV resources

Let’s create an ordered sequence in rs schema and then query values from the sequence few times.

create sequence rs.test_seq order cache 100;
select rs.test_seq.nextval from dual; -- repeated a few times.
...
/
21

Sequence values are permanently stored in the seq$ dictionary table. Cached sequence values are maintained in SV resources in GRD and SV resource names follows the naming convention to include object_id of the sequence. I will generate a string using a small helper script and we will use that resource name to search in the GRD.

SELECT DISTINCT '[0x'
    ||trim(TO_CHAR(object_id, 'xxxxxxxx'))
    ||'][0x'
    || trim(TO_CHAR(0,'xxxx'))
    || '],[SV]' res
FROM dba_objects WHERE object_name=upper('&objname')
     AND owner=upper('&owner') AND object_type LIKE 'SEQUENCE%'
/
Enter value for objname: TEST_SEQ
Enter value for owner: RS
RES
---------------------------
[0x165d7][0x0],[SV]

Read the rest of this entry »

Posted in 12c, Oracle database internals, Performance tuning, RAC, weird stuff | Tagged: , , , , , | 2 Comments »

 
Follow

Get every new post delivered to your Inbox.

Join 264 other followers