Thank you, Larry Ellison

My colleague Vince Westin published this great post on his blog:

During his opening keynote at Oracle OpenWorld 2012, Larry Ellison launched the new Exadata X3.
LarryOOW2012 The new version appears to have some nice new capabilities, including caching writes to EFD, which are likely to improve the usability of Exadata for OLTP workloads. And he was nice enough to include the EMC Symmetrix VMAX 40K in detail on 30% of his slides as he announced the new Exadata. And for that, I give thanks. I am sure that Salesforce.com were similarly thankful when Larry focused so much of his time on their product in his keynote last year.

Read the rest of his post here.

The post provides a bunch of good reasons why EMC VMAX might be a better choice for customers that run high-performance mission-critical environments. A highly recommended read!

Data Guard protecting from EMC block corruptions?

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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Oracle and Data Integrity: Data in, Garbage Out?

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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Data Guard or Storage based replication?

A comparison between Oracle (Active) Data Guard and EMC replication for disaster recovery purposes

Panic Button
This is an article I wrote a while ago for customers’ Database Administrators (DBAs) and application managers, that helps them in selecting the right Disaster Recovery tools for their business applications.
It is slightly modified to update new insights and to make it more readable on the web.

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Eliminate Hot Backup with EMC consistency technology

For many years, EMC customers have been using storage replication technology to create copies of entire databases. Using storage cloning has many advantages over other mechanisms (file copy, tape restore, and the like). Most significant is that EMC storage can create near-instant copies of large applications without significant performance overhead. The reason is that the storage system is using its huge internal bandwidth and a couple of smart tricks to create the copy, therefore bypassing the host I/O layer.

Cloning

Cloning

In other words, a server running a database does not have to move a single bit of data for creating a copy of a multi-terabyte database.

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Duplexing Oracle Redo logs?

A customer asked me recently what EMC’s advice is regarding duplexing Oracle redo logs. There is a thought behind this – Oracle redo logs are sensitive to data corruption – if redo logs are corrupt, there is no way to nicely recover the database to a technically consistent state (at least not without restoring data from backups).

This is what Oracle tells you:

Oracle recommends that you multiplex your redo log files; the loss of the log file information can be catastrophic if a recovery operation is required.

 

Duplexed Redo

Duplexed Redo


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