The Quick and Dirty Dedupe Analyzer – Part 1 – Hands on

As announced in my last blogpost, qdda is a tool that analyzes potential storage savings by scanning data and giving a deduplication, compression and thin provisioning estimate. The results are an indication whether a modern All-Flash Array (AFA) like Dell EMC XtremIO would be worth considering.

In this (lenghty) post I will go over the basics of qdda and run a few synthetic test scenarios to show what’s possible. The next posts will cover more advanced scenarios such as running against Oracle database data, multiple nodes and other exotic ones such as running against ZFS storage pools.

[ Warning: Lengthy technical content, Rated T, parental advisory required ]

Introducing Outrun for Oracle

Overview

If 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 12.1.0.1 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 12.1.0.2 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.

Starting an Oracle database on physical server using VMware VMDK volumes

By now, we all know Oracle is fully supported on VMware. Anyone telling you it’s not supported is either lying to you, or doesn’t know what he is talking about (I keep wondering what’s worse).

VMware support includes Oracle RAC (if it’s version 11.2.0.2.0 or above).  However, Oracle may request to reproduce problems on physically deployed systems in case they suspect the problem is related to the hypervisor. The support note says:

Oracle will only provide support for issues that either are known to occur on the native OS, or can be demonstrated not to be as a result of running on VMware.

In case that happens, I recommend to contact VMWare support first because they might be familiar with the issue or can escalate the problem quickly. VMware support will take full ownership of the problem. Still, I have met numerous customers who are afraid of having to reproduce issues quickly and reliably on physical in case the escalation policy does not help. We need to get out of the virtual world, into reality, without making any other changes.  How do we do that?

Limitations of host-based mirroring for stretched clusters

For data mirroring, EMC SRDF is sometimes used in such a setup that both servers write to one location only (the “far” server writes across dark fibre links to the local storage). EMC has similar tools (Mirrorview, Recoverpoint, etc) for other storage platforms than Symmetrix.

SRDF cluster with passive target

Why use Oracle ASM for Oracle databases

I’ve been in discussions with some customers recently about what is the best way to store Oracle database data. Needless to say that the foundation should be EMC infrastructure of course, but apart from that, what kind of volume manager and/or filesystem works best for performance and other features?

There are many volume managers, and many filesystems available, more or less dependent on what hardware and operating system you run the database.

Some have a long track record, some are new kids on the block. Some are part of the operating system, others are 3rd party add-ons, for which you might need to pay licenses.

One way of storing Oracle database data is Oracle ASM.