Archive Page 2

How Do I Know I Have The Latest SLOB Kit?

This is a quick blog post to show SLOB users how to determine whether they are using the latest SLOB kit. If you visit kevinclosson.net/slob you’ll see the webpage I captured in the following screenshot.

Once on the SLOB Resources page you can simply hover over the “SLOB 2.2 (Click here)” hyperlink and the bottom of your browser will show the full name of the tar archive. Alternatively you can use md5sum(1) on Linux (or md5 on Mac) to get the checksum of the tar archive you have and compare it to the md5sum I put on the web page (see the arrow).

 

latest-slob

Announcing XtremIO Performance Engineering Lab Report: Facts About Redo Logging And NAND Flash.

I invite you to please read this report.

NAND Flash is good for a lot of things but not naturally good with write-intensive workloads. Unless, that is, skillful engineering is involved to mitigate the intrinsic weaknesses of NAND Flash in this regard. I assert EMC XtremIO architecture fills this bill.

Regardless of your current or future plans for adopting non-mechanical storage I hope this lab report will show some science behind how to determine suitability for non-mechanical storage–and NAND Flash specifically–where Oracle Database redo logging is concerned.

Please note: Not all lab tests are aimed at achieving maximum theoretical limits in all categories. This particular lab testing required sequestering precious lab gear for a 104 hour sustained test.

The goal of the testing was not to show limits but, quite to the contrary, to show a specific lack of limits in the area of Oracle Database redo logging. For a more general performance-focused paper please download this paper (click here).  With that caveat aside, please see the following link for the redo logging related lab report:

Link to XtremIO Performance Engineering Lab Report (click here).

 

Redo-Durability-splash

Announcing SLOB 2.2 : Think Time and Limited-Scope User-Data Modification

This is a hasty blog post to get SLOB 2.2 out to those who are interested.

Where To Get The Kit

Please visit kevinclosson.net/slob

 

About The New Kit

In addition to doing away with the cumbersome “seed” table and procedure.sql, this kit introduces 5 new slob.conf parameters. By default these parameters are disabled.

This SLOB distribution does not require re-executing setup.sh. One can simply adopt the kit and use it to test existing SLOB databases. The following explains the new slob.conf parameters:

DO_UPDATE_HOTSPOT=FALSE

When set to TRUE, modify SQL will no longer affect random rows spanning each session’s schema. Instead, each session will only modify HOTSPOT_PCT percent of their data.

HOTSPOT_PCT=10

This parameter controls how much of each session’s schema gets modified when UPDATE_PCT is non-zero. The default will limit the scope of each session’s data modifications to a maximum of 10% of their data.

THINK_TM_MODULUS=0

When set to non-zero this is a frequency control on how often sessions will incur think time. For example, if set to 7, every seventh SQL statement will be following by a sleep (think time) for a random amount of time between THINK_TM_MIN and THINK_TM_MAX. It’s best to assign a prime number to THINK_TM_MODULUS.

THINK_TM_MIN=.1

The low-bound for selection of a random period to sleep when THINK_TM_MODULUS triggers a think time event.

THINK_TM_MAX=.5

The high-bound for selection of a random period to sleep when THINK_TM_MODULUS triggers a think time event.

Notes About Think Time

The resolution supported for think time is hundredths of a second.

Additional Helpful Files

The additional tarball (at the following link) has a slob.conf, simple.ora and awr.txt that show a way to have 256 sessions produce the following load profile (on 2s16c32t E5 Xeon):

https://my.syncplicity.com/share/geydubw3q42okrt/think-time-help-files.tar

load-profile-think-time

Quick Links to Helpful Literature on Oracle Database In-Memory Column Store.

I’m surprised to find that Google is not cleanly ranking the helpful set of blog posts by Oracle’s Maria Colgan on the Oracle Database 12c In-Memory Column Store feature so I thought I’d put together this convenient set of links. Google search seems to only return a few of them in random order.

Over time I may add other helpful links regarding Oracle’s new, exciting caching technology.

Starter Information

Getting Started With Oracle Database In-Memory. Part I.

Getting Started With Oracle Database In-Memory. Part II.

Getting Started With Oracle Database In-Memory. Part III.

Getting Started With Oracle Database In-Memory. Part IV. 

In-Memory Column Store With Real Application Clusters

The following are links to information about Oracle Database In-Memory on Real Application Clusters:

Oracle Database In-Memory on RAC. Part I.

In-Memory Product That Requires Proprietary Storage?

How could the brand of storage matter for an in-memory cache feature? Good question.

Fellow Oaktable Network member Christian Antognini has produced a very important article regarding how Oracle Database 12c In-Memory Column Store with Real Application Clusters is questionable unless using Oracle storage (Exadata, SPARC SuperCluster).  I found Christian’s article very interesting because, after all, the topic at hand is an in-memory cache product (a.k.a., In-Memory Column Store). I fail to see any technical reason why Oracle wouldn’t support an in-memory product with blocks from any and all storage. It is in-memory after all, isn’t it? Please visit Christian’s article here: The Importance of the In-Memory DUPLICATE Clause for a RAC System.

 

 

 

 

 

SLOB Patch. AWR Post-Processing Script (awr_info.sh) Fix.

BLOG UPDATE 2015.01.20: Please Note! This patch has been deprecated. Please go to kevinclosson.net/slob to get the latest SLOB kit with the latest awr_info.sh.

BLOG UPDATE 2014.09.11: Please note: the following is a link to a more recent update of the awr_info.sh script. This version adds DB Time, DB CPU and Logical I/O: click here. The MD5 sum for this version of awr_info.sh is:  a28a38b11040bb94f08a8f817792c75c

The SLOB kit comes with a little script that extracts interesting information from the awr.txt file produced at the end of a SLOB test. This is just a quick blog entry to point folks to a patched version of awr_info.sh that works properly with all Oracle Database 11g releases as well as Oracle Database 12c.

Oracle changed AWR format in the 11.2.0.4 and 12c releases so the old awr_info.sh script (in the publicly available SLOB kit) has been faulty for some time now.

I have a release of SLOB in the works that will include this awr_info.sh as well as improved data loader and improvements to the driver script (runit.sh) that includes optional, tunable think time between iterations of the SLOB work loop in slob.sql. For the time being please get a copy of the patched version of awr_info.sh.

New awr_info.sh Output

This version of awr_info.sh also gleans and outputs logical read (SGA buffer pool cached block accesses) data.

The following screen shot shows the patched awr_info.sh generating proper output for awr.txt files collected by SLOB databases running out of the 11.2.0.3, 11.2.0.4 and 12c releases.

2014.09.11-awr_info-example

The following picture is what Microsoft Excel looks like when I cut and paste the output of awr_info.sh. I’ve highlighted the new column for logical reads.

2014.09.11-awr_info-xls-example

Exadata Cell Single Block Physical Reads?

Yes, the above picture does show AWR output from a run where the top wait event was cell single block physical read. Exadata? Yes! That’s because SLOB users often share their testing results from the Exadata platform.  However, I do not get enough Exadata AWR reports to work through all of the awr_info.sh issues related to Exadata. To that end, latency information is not calculated and presented as is the case with db file sequential read. For what it’s worth this particular AWR report shows Exadata single block reads serviced with average latencies of 507 microseconds ( 7233/14256602).

Where To Get The Patch?

BLOG UPDATE 2014.12.09: Please Note! The following awr_info.sh readme and script supercede all prior versions mentioned in this blog:

Patch README

awr_info.sh patch

 

SLOB Failing To Generate AWR Reports? Red Hat Bug 919793!

This is a quick blog post to help folks that are testing with SLOB at high user (session) counts. The situation may arise where you are testing SLOB on a large configuration, with or without SQL*Net, and the SLOB driver (runit.sh) is failing to produce Automatic Workload Repository (a.k.a AWR) reports.

This problem will generally be seen on RHEL 6 variants that implement the much maligned /etc/security/limits.d/90-nproc.conf method of preventing fork bombs. For more information on this configuration file please refer to Red Hat bug 919793.

If you are not getting AWR reports under the condition I describe then the problem is most likely due to 90-nproc.conf short circuiting the ulimit(3) tuning you’ve established.

As an example remedy, please consider the following settings I recommended to my colleagues at VCE for performance testing of the vBlock Specialized System for High Performance Databases:

SS-HPDB-fork-bomb

 

 

XtremIO @ Tech Field Day 2014

kevinclosson:

As scientists, interested in what’s happening in platform technology, readers of my blog will find my colleague Itzik Reich’s recent blog on EMC XtremIO to be very informative. Enjoy!

Originally posted on Itzikr's Blog:

image

Hi,

during the week of VMworld 2014, we had the pleasure of presenting in front of the audience of the tech field day delegates.

attached below are the links to the session Josh Goldstein delivered, enjoy!

EMC XtremIO Introduction

EMC XtremIO Architecture – Consistent and Predictable Performance

EMC XtremIO Data Services

View original


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All content is © Kevin Closson and "Kevin Closson's Blog: Platforms, Databases, and Storage", 2006-2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Kevin Closson and Kevin Closson's Blog: Platforms, Databases, and Storage with appropriate and specific direction to the original content.

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