Announcing Obfuscated Column Data Loading with SLOB

| Nov 19, 2019

On November 18, 2019 I announced availability of SLOB 2.5.2. It is primarily a small bug fix release but also has an undocumented new feature. I want to say a few words about the feature in this post and will update SLOB with full support (e.g., documentation and slob.conf parameter support) in SLOB 2.5.3.  Some SLOB users might want this new undocumented feature as soon as possible–thus (more...)

Announcing SLOB 2.5.2

| Nov 18, 2019

SLOB 2.5.2 is available for download from Github. Please visit the SLOB Resources Page for the download URLs.

SLOB 2.5.2 is a bug fix release.

So pgio Does Not Accurately Report Physical I/O In Test Results? Buffering Buffers, and Baffles.

| Sep 27, 2019

A new user to pgio (The SLOB Method for PostgreSQL) reached out to me with the following comment:

 I’ve been testing with pgio but when I compare I/O monitored in iostat output it does not match the pgio output for physical reads. 

The user is correct–but that’s not the fault of pgio. Please allow me to explain.

Buffering Buffers, and Baffles

PostgreSQL does not open files with the O_DIRECT flag which means I/O performed (more...)

Announcing pgio (The SLOB Method for PostgreSQL) Is Released Under Apache 2.0 and Available at GitHub

| Sep 21, 2019

This is just a quick post to advise readers that I have released pgio (The SLOB Method for PostgreSQL) under Apache 2.0. The bits are available at the following link: The README is quite informative.

My last testing before the release showed “out of the box” data loading into Amazon Aurora with PostgreSQL compatibility at a rate of 1.69 TB/h. I only modified the pgio.conf file to specify the connection (more...)

Announcing SLOB 2.5 for Download at Github.

| Sep 18, 2019

This is just a quick blog post to announce that SLOB 2.5 is now available for downloading at:

There is an important bug fix in this release that corrects redo logging payload generation when testing with non-zero slob.conf->UPDATE_PCT.  I recommend downloading and using this release accordingly.  The bug is described in the release notes.

A special thanks to Maris Elsins for finding, blogging and reporting the bug.


Accurately Interpreting Real Application Clusters IOPS with Automatic Workload Repository. So Easy to Get So Wrong.

| Oct 13, 2018

This blog post has been necessary for quite some time but I just now finally got around to posting it. What I’m going to blog about is a common problem I run into in my dealings with Oracle Database Administrators (DBAs). It’s about IOPS data in Automatic Workload Repository (AWR) reports. Please don’t roll your eyes. Not everyone gets this right. I’ll explain…

I cannot count how many times I’ve had DBAs cite some IOPS (more...)

No /proc/diskstats Does Not Track **Your** Physical I/O Requests

| Oct 9, 2018

You have applications that scan disk using large sequential reads so you take a peek at /proc/diskstats (field #4 on modern Linux distributions) before and after your test in order to tally up the number of reads your application performed. That’s ok. That’s also a good way to get erroneous data.

Your application makes calls for I/O transfers of a particular size. The device drivers for your storage might not be able to accommodate your (more...)

SLOB Chewed Up All My File System Space and Spit It Out. But, Why?

| Oct 1, 2018

This is a quick blog post in response to a recent interaction with a SLOB user. The user reached out to me to lament that all her file system space was consumed as the result of a SLOB execution ( I reminded her that will alert to possible derelict mpstat/iostat/vmstat processes from an aborted SLOB test. If these processes exist they will be spooling their output to unlinked files.

The following screen (more...)

Sneak Preview of pgio (The SLOB Method for PostgreSQL) Part IV: How To Reduce The Amount of Memory In The Linux Page Cache For Testing Purposes.

| May 23, 2018

I hope these sneak peeks are of interest…

PostgreSQL and Buffered I/O

PostgreSQL uses buffered I/O. If you want to test your storage subsystem capabilities with database physical I/O you have to get the OS page cache “out of the way”–unless you want to load really large test data sets.

Although pgio (the SLOB Method for PostgreSQL) is still in Beta, I’d like to show this example of the tool I provide for users to (more...)

Sneak Preview of pgio (The SLOB Method for PostgreSQL) Part III: Link To The Full README file for Beta pgio v0.9.

| May 22, 2018

If you are interested in a head start on pgio, the following is a link to the full README file which has some loading and testing how-to:

The pgio text README file version 0.9 Beta

Sneak Preview of pgio (The SLOB Method for PostgreSQL) Part II: Bulk Data Loading.

| May 22, 2018

Bulk Data Loading With pgio Version 0.9 Beta

Now that pgio (the SLOB Method for PostgreSQL) is in Beta users’ hands I’m going to make a few quick blog entries with examples of pgio usage. The following are screen grabs taken while loading 1 terabyte into the pgio schemas. As the example shows, pgio (on a system with ample storage performance) can ready a 1 terabyte data set for testing in only 1014 seconds (more...)

Sneak Preview of pgio (The SLOB Method for PostgresSQL) Part I: The Beta pgio README File.

| May 22, 2018

The pgio kit is the only authorized port of the SLOB Method for PostgreSQL. I’ve been handing out Beta kits to some folks already but I thought I’d get some blogs posts underway in anticipation of users’ interest.

The following is part of the README.txt for pgio v0.9 (Beta). SLOB users will find it all easy to understand. This is the section of the README that discusses pgio.conf parameters:

The percentage  (more...)

SLOB Can Now Be Downloaded From GitHub.

| Apr 16, 2018

This is a quick blog entry to announce that the SLOB distribution will no longer be downloadable from Syncplicity. Based on user feedback I have switched to making the kit available on GitHub. I’ve updated the LICENSE.txt file to reflect this distribution locale as authorized and the latest SLOB version is

Please visit for more information.


Whitepaper Announcement: Migrating Oracle Database Workloads to Oracle Linux on AWS

| Apr 4, 2018

This is just a quick blog entry to share a good paper on migrating Oracle Database workloads to Amazon Web Services EC2 instances running Oracle Linux.

Please click the following link for a copy of the paper:  Click Here.


White Paper Announcement: Benchmarking Amazon Aurora.

| Mar 31, 2018

This is just a quick blog post to inform readers of a good paper that shows some how-to information for benchmarking Amazon Aurora. This is mostly about sysbench which is a test the transactional capabilities.

As an aside, many readers my have heard that I’m porting SLOB to PostgreSQL and will make that available in May 2018. It’ll be called “pgio” and is an implemention of the SLOB Method as described in the SLOB documentation. (more...)

A Word About Amazon EBS Volumes Presented As NVMe Devices On C5/M5 Instance Types.

| Feb 21, 2018

If It Looks Like NVMe And Tastes Like NVMe, Well…

As users of the new Amazon EC2 C5 and M5 instance types are noticing, Amazon EBS volumes attached to C5 and M5 instances are exposed as NVMe devices. Please note that the link I just referred to spells this arrangement out as the devices being “exposed” as NVMe devices. Sometimes folks get confused over the complexities of protocol, plumbing and medium as I tend to (more...)

Testing Amazon RDS for Oracle: Plotting Latency and IOPS for OLTP I/O Pattern

| Oct 10, 2017

This is just a quick blog entry to direct readers to an article I recently posted on the AWS Database Blog. Please click through to give it a read:

Thanks for reading my blog!


Filed under: oracle

Little Things Doth Crabby Make – Part XXII. It’s All About Permissions, Dummy. I Mean yum(8).

| Aug 4, 2017

Good grief. This is short and sweet, I know, but this installment in the Little Things Doth Crabby Make series is just that–short and sweet. Or, well, maybe short and sour?

Not root? Ok, yum(8), spew out a bunch of silliness at me. Thanks.

Sometimes, little things doth, well, crabby make!

Hey, yum(8), That is Ridiculous User Feedback

Filed under: oracle

Step-By-Step SLOB Installation and Quick Test Guide for Amazon RDS for Oracle.

| Jul 25, 2017

Before I offer the Step-By-Step guide, I feel compelled to answer the question that some exceedingly small percentage of readers must surely have in mind–why test with SLOB? If you are new to SLOB (obtainable here) and wonder why anyone would test platform suitability for Oracle with SLOB, please consider the following picture and read this blog post.

SLOB Is How You Test Platforms for Oracle Database.

Simply put, SLOB is the right tool (more...)

Little Things Doth Crabby Make – Part XXI. No, colrm(1) Doesn’t Work.

| Jul 13, 2017

This is just another quick and dirty installment in the Little Things Doth Crabby Make series. Consider the man page for the colrm(1) command:

That looks pretty straightforward to me. If, for example, I have a 6-column text file and I only want to ingest from, say, columns 1 through 3,  I should be able to execute colrm(1) with a single argument: 4. I’m not finding the colrm(1) command to work in accordance with my (more...)