The Quick and Dirty Deduplication Analyzer

The best thing about being me… There are so many “me”s.

— Agent Smith, The Matrix Reloaded

One of our customers reported less than optimal space savings on XtremIO running Oracle. In order to test various scenarios with Oracle I was in search of a deduplication analysis method or tool – only to find out that there was nothing available that qualified.

TL;DR: QDDA is an Open Source tool I wrote to analyze Linux files, devices or data streams for duplicate blocks and compression estimates. It can quickly give you an idea of how much storage savings you could get using a modern All-Flash Array like XtremIO. It is safe to use on production systems and allows quick analysis of various test scenarios giving direct results, and even works with files/devices that are in use. No registration or uploading of your confidential data is required.

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The IOPS race is over

emc-f1-carInfrastructure has always been a tough place to compete in. Unlike applications, databases or middleware, infrastructure components are fairly easy to replace with another make and model, and thus the vendors try to show off their product as better than the one from the competition.

In case of storage subsystems, the important metrics has always been performance related and IOPS (I/O operations per second) in particular.

I remember a period when competitors of our high-end arrays (EMC Symmetrix, these days usually just called EMC VMAX) tried to artificially boost their benchmark numbers by limiting the data access pattern to only a few megabytes per front-end IO port. This caused their array to handle all I/O in the small memory buffer cache of each I/O port – and none of the I/O’s would really be handled by either central cache memory or backend disks. This way they could boost their IOPS numbers much higher than ours. Of course no real world application would ever only store a few megabytes of data so the numbers were pure bogus – but marketing wise it was an interesting move to say the least.

With the introduction of the first Sun based Exadata (the Exadata V2) late 2009, Oracle also jumped on the IOPS race and claimed a staggering one million IOPS. Awesome! So the gold standard was now 1 million IOPS, and the other players had to play along with the “mine’s bigger than yours” vendor contest.
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Baking a cake: trading CPU for IO?

Sometimes I hear people claim that by using faster storage, you can save on database licenses. True or false?

The idea is that many database servers are suffering from IO wait – which actually means that the processors are waiting for data to be transferred to or from storage – and in the meantime, no useful work can be done. Given the expensive licenses that are needed for running commercial database software, usually licensed per CPU core, this then leads to loss of efficiency.

Let’s see if we can visualise the problem here with a common world example – Baking a cake.

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Silly Little Oracle Benchmark – RPM edition

slob-rpmA while ago Kevin Closson announced a new release of the well-known SLOB kit.

SLOB is a simple but powerful toolkit that drives lots and lots of IO on a real Oracle database (so for performance testing of database platforms, it’s much better than synthetic IO tests).

A previous version was bundled with Outrun but required the entire Outrun distribution to work properly. With the new 2.3 version I created an RPM package that can be installed separate on any Enterprise Linux 6.x (64 bit) server.

The wiki page (including instructions) can be found here: SLOB RPM Package wiki

Thanks to Kevin for granting permission to redistribute this awesome toolkit!

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Introducing Outrun for Oracle


outrun-logo-transparentIf you want to get your hands dirty with Oracle database, the first thing you have to do is build a system that actually runs Oracle database. Unless you have done that several times before, chances are that this will take considerable time spent on trial-and-error, several reinstalls, fixing install problems and dependencies and so on. The time it takes for someone who is reasonably experienced on Linux, but has no prior Oracle knowledge, would probably range from a full working day (8 hours, best case) to many days. I also have witnessed people actually giving up.

Even for experienced users, doing the whole process manually over and over again is very time consuming, and deploying five or more systems by hand is a guarantee that each one of them is slightly different – and thus a candidate for subtle problems that happen on one but not the others. Virtualization and consolidation is all about consistency and making many components as if they were only one.

There are literally dozens of web pages (such as blog posts) that contain detailed instructions on how to set up Oracle on a certain platform. Some examples:

The Gruff DBA – Oracle 12cR1 2-node RAC on CentOS 6.4 on VMware Workstation 9 – Introduction
Pythian – How to Install Oracle 12c RAC: A Step-by-Step Guide
Martin Bach – Installing Oracle RAC on Oracle Linux 7-part 1

Even if you follow the guidelines in such articles, you are likely to run into problems due to running a different OS, different Oracle version, network problems, and so on. Not to mention that in many cases the “best practices” provided by various vendors are often not honoured because they tend to be overlooked due to information overload…

Some people have hinted to use automated deployment tools such as Ansible (i.e. Frits Hoogland – Using Ansible for executing Oracle DBA tasks) but there are (as far as I know) no complete out-of-the-box solutions.

EMC has published several white papers and reference architectures with instructions on how to set up Oracle to run best on EMC. Still, some of the papers are not a step-by-step manual so you have to extract configuration details manually from various (sometimes conflicting) sources and convert them in configuration file entries, commands, etc.

So I decided a while ago to go for a different approach, and build a virtual appliance that does all of these things for you while still offering (limited) flexibility in different platform and versions, and preferences for configuration.

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Oracle Data Placement on XtremIO

Many customers these days are implementing Oracle on XtremIO so they benefit from excellent, predictable performance and other benefits such as inline compression and deduplication, snapshots, ease of use etc.

Those benefits come at a price and if you just consider XtremIO on a usable gigabyte basis, it does not come cheap. Things change if you calculate the savings due to those special features. Still, customers are trying to get the best bang for the buck, and so I got a question from one customer if it would make sense to place only Oracle datafiles on XtremIO and leave everything else on classic EMC storage. This would mean redo logs, archive logs, control files, temp tables, binaries and everything else, *except* the datafiles, would be stored on an EMC VNX or VMAX. The purpose of course is to only have things that require fast random reads (the tables) on XtremIO.

I can clearly see the way of thinking but my response was to change the layout slightly. I highly recommend to place everything that is needed to make up a database in a consistent way, on the same storage box.

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Oracle ASM vs ZFS on VNX

swiss-cheeseIn my last post on ZFS I shared results of a lab test where ZFS was configured on Solaris x86 and using XtremIO storage. A strange combination maybe but this is what a specific customer asked for.

Another customer requested a similar test with ZFS versus ASM but on Solaris/SPARC and on EMC VNX. Also very interesting as on VNX we’re using spinning disk (not all-flash) so the effects of fragmentation over time should be much more visible.

So with support of the local administrators, I performed a similar test as the one before: start on ASM and get baseline random and sequential performance numbers, then move the tablespace (copy) to ZFS so you start off with as little fragmentation as possible. Then run random read/write followed by sequential read, multiple times and see how the I/O behaves.
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Oracle ASM vs ZFS on XtremIO


In my previous post on ZFS I showed how ZFS causes fragmentation for Oracle database files. At the end I promised (sort of) to also come back on topic around how this affects database performance. In the meantime I have been busy with many other things, but ZFS issues still sneak up on me frequently. Eventually, I was forced to take another look at this because of two separate customers asking for ZFS comparisons agaisnt ASM at the same time.

The account team for one of the two customers asked if I could perform some testing on their lab environment to show the performance difference between Oracle on ASM and on ZFS. As things happen in this business, things were already rolling before I could influence the prerequisites and the suggested test method. Promises were already made to the customer and I was asked to produce results yesterday.

Without knowledge on the lab environment, customer requirements or even details on the test environment they had set up. Typical day at the office.

In addition to that, ZFS requires a supported host OS – so Linux is out of the question (the status on kernel ZFS for Linux is still a bit unclear and certainly it would not be supported with Oracle). I had been using FreeBSD in my post on fragmentation – because that was my platform of choice at that point (my Solaris skills are, at best, rusty). Of course Oracle on FreeBSD is a no-go so back then, I used NFS to run the database on Linux and ZFS on BSD. Which implicitly solves some of the potential issues whilst creating some new ones, but alas.

Solaris x86

This time the idea was to run Oracle on Solaris (x86) that had both ZFS and ASM configured. How to perform a reasonable comparison that also shows the different behavior was unclear and when asking that question to the account team, the conference call line stayed surprisingly silent. All that they indicated up front is that the test tool on Oracle should be SLOB.

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Getting the Best Oracle performance on XtremIO

(Blog repost from Virtual Storage Zone – Thanks to @cincystorage)

UPDATE: I’ll say it again because there seems to be some confusion: THIS IS A REPOST!

Original content is from the Virtual Storage Zone blog (not mine). Just reposted here because it’s interesting and related to Oracle, performance and EMC storage. Enjoy…

XtremIO is EMC’s all-flash scale out storage array designed to delivery the full performance of flash. The array is designed for 4k random I/O, low latency, inline data reduction, and even distribution of data blocks.  This even distribution of data blocks leads to maximum performance and minimal flash wear.  You can find all sorts of information on the architecture of the array, but I haven’t seen much talking about archive maximum performance from an Oracle database on XtremIO.

The nature of XtremIO ensures that’s any Oracle workload (OLTP, DSS, or Hybrid) will have high performance and low latency, however we can maximize performance with some configuration options.  Most of what I’ll be talking about is around RAC and ASM on Redhat Linux 6.x in a Fiber Channel Storage Area Network.

Read the full blogpost here.


TheCube interview EMC World 2014

Being interviewed yesterday at EMC World 2014 by Wikibon and SiliconAngle.


Bart @ The Cube

Update: You can find a report of the interview here: Best Practices for Putting Your Oracle Database into the Cloud