Dirty Cache

Oracle RAC on VPLEX now certified

Bart Sjerps 2012-05-20 Innovation, Oracle, VPLEX

Last week EMC announced that Oracle RAC on VPLEX stretched clusters is now officially supported and certified by Oracle!

News Summary:

Oracle has certified that EMC® VPLEX™ METRO in a stretch cluster configuration can provide Oracle Real Application Clusters (Oracle RAC) customers with an easy-to-deploy, active/active solution, as they transform from single- to dual-site environments.

Having passed Oracle’s rigorous testing standards, the EMC VPLEX METRO solution can enable Oracle RAC to be easily configured over extended distances while enabling simultaneous access to the same data at both locations.

This is the final step in a process to help customers that have been asking for true active/active support over distance for their mission-critical Oracle Database business processes.

For those who are not yet familiar with this solution, here is a small summary:

Customers have been in search for ways to survive datacenter failures (i.e. “disasters”) without the need to recover and restart the databases, in such a way that any component failure or even complete site failure would not lead to database downtime
This was not possible before except when deploying complex configurations based on host mirroring using Oracle ASM or a 3rd party volume manager. (note that competing storage virtualization products from other storage vendors also do not offer this full capability – even though their marketing might make it seem so)
EMC VPLEX offers this functionality which is now completely certified and supported by Oracle, and the solution avoids risk by making the stretched cluster deployment as easy as a basic Oracle RAC install
The VPLEX solution offers additional benefits including better performance, better recovery from issues such as component or link failures and offers a complete solution for the whole application stack, not just Oracle
Note that AFAIK this solution should also work for IBM DB2 (but I haven’t confirmed)

The full news release can be found here: http://www.emc.com/about/news/press/2012/20120517-04.htm

A full series of blog posts on this solution can be found here: http://dirty-cache.com/category/vplex/

The VPLEX witness (the final component of VPLEX that made this possible) was announced last year at EMC World 2011. Typically we see the start of market adoption between 1 to 1.5 years after bringing new technology in the market. I am working on a few customers myself who are on the edge of starting a project with this, hopefully by the end of year we have a set of good customer references!

Update: The new white paper can be found here: http://www.emc.com/collateral/software/white-papers/h8930-vplex-metro-oracle-rac-wp.pdf

Update 2: VPLEX support mentioned (briefly) on Oracle’s website: http://www.oracle.com/technetwork/database/enterprise-edition/tech-generic-linux-new-086754.html

Update 3: Demos available on EMC Demo Center:

EMC VPLEX Metro for Oracle RAC Solution Overview
Oracle RAC with VPLEX Metro Site Failure
Oracle RAC with VPLEX Metro Solution Overview
Oracle RAC with VPLEX Storage Failure

If you’re a frequent reader of my blog you might recognize familiar pictures there 😉

Data Guard protecting from EMC block corruptions?

Bart Sjerps 2012-04-16 Oracle

Today I was giving a training to fellow EMC colleagues on some Oracle fundamentals. One of the things that was mentioned is something I have heard several times before: Oracle is claiming that EMC SRDF (a data mirroring function from EMC Symmetrix enterprise storage systems mainly to provide enterprise disaster recovery functions) cannot detect certain types of data corruption where Oracle Data Guard can. Ouch. The trouble with this statement is that it is half-true (and these ones are the most dangerous).
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Performance – The database stack

Bart Sjerps 2012-02-15 Oracle, Performance

hamb-stack As mentioned before, I frequently find myself in discussions around Oracle performance and how an Oracle database behaves on EMC storage. It turns out that often there is a lot of confusion on how the different layers interact with each other and very few people seem to understand the whole stack.

So I started a personal challenge to make a “one picture tells more than 1000 words” complete overview of the Oracle on EMC database stack.

I failed.

Turns out it’s nearly impossible to get everything in one picture without cutting corners.

So here is a simplified (and therefore incorrect) picture. It ignores certain complexities and is far from complete, and might even contain errors.

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Wikipedia blackout

Bart Sjerps 2012-01-17 Various

Just to inform you that tomorrow (wednesday jan. 18th, 2012), some of the links on my blog might not work due to Wikipedia’s one-day blackout, in protest against SOPA (and I use Wikipedia a lot as a great resource to learn from myself, and to point to my readers for more information on certain topics).

I think Wikipedia touches a true problem; governments (pushed by lobbyist groups) are pushing for an internet where you have to be cautious about what you say or publish. Best case, you might get blacklisted. Worst case? Figure it out for yourself.

I live in the Netherlands and currently something similar is going on about organizations trying to restrict people accessing certain information sources (in this case, the Pirate Bay). Whether Pirate Bay (or any other source of information for that matter) violates the law, or not, is (IMO) a different discussion. But if people (or organizations) want to restrict access by ordering ISP’s (information service providers, a.k.a. the mailman) to blacklist those sites (i.e. check your mail for offending content) instead of chasing the publishers of illegal materials of any kind, then we are well on our way to a different internet. An internet that is no longer free. I strongly oppose to that.

So, Wikipedia (and others), you have my full support.

Click the “STOP SOPA” banner (top right hand corner) if you want to learn more.

More info:

https://www.eff.org/deeplinks/2011/12/fight-blacklist-toolkit-anti-sopa-activists

https://www.eff.org/search/site/sopa

Oracle and Data Integrity: Data in, Garbage Out?

Bart Sjerps 2011-12-14 Oracle

Stop Corruption

A trivial question:

What is the basic function of a storage system?
I would say, the trivial function of a storage system is to store digital data and getting it back when you need it.

To be specific:
get the data back exactly the way you stored it.

You would probably say “Duh, of course!”

A storage system (as simple as a hard disk or as sophisticated as an EMC VMAX) is supposed to store data and give it back unmodified. But recent research shows that simple disk drives are not as reliable as you might think. Enough material is available that explains why and how often disk drives fail to return the correct information, often without any error as if the corrupted data is perfectly valid. See below for more references to this issue.

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