The EMC Oracle Joint Escalation Center

Oracle & EMCEMC and Oracle have supported each others products since 1995 and both spent millions of dollars in making them work together. EMC actually became famous in the late nineties because of our “Guilty until proven innocent” support mentality. We are known for the first company to give meaning to the concept of “Remote Support / Phone Home”, and the success stories still go around that EMC field engineers sometimes surprised customers with a visit in order to repair components (mostly disk drives), often before they were broken, and if they were actually broken the customers would not even notice (needless to say that replacements were done online).

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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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Performance – The database stack

hamb-stackAs 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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Monkey Business

Monkey eating bananaMaybe you have heard the story of the Monkey Experiment. It is about an experiment with a bunch of monkeys in a cage, a ladder, and a banana. At a certain point one of the monkeys sees the banana hanging up high, starts climbing the ladder, and then the researcher sprays all monkeys with cold water. The climbing monkey tumbles down before even getting the banana, looks puzzled, wait until he’s dry again and his ego back on its feet. He tries again, same result, all monkeys are sprayed wet. Some of the others try it a few times until they learn: don’t climb for the banana or you will get wet and cold.

The second part of the experiment becomes more interesting. The researcher removes one of the monkeys and replaces him with a fresh, dry monkey with an unharmed ego. After a while he spots the banana, wonders to himself why the other monkeys are so stupid not to go for the banana, and gives it a try. But when reaching the ladder, the other monkeys kick his ass and make it very clear he is not supposed to do so. After the new monkey is conditioned not to go for the banana, the researcher replaces the “old” monkeys, one by one, with new ones. Every new monkey goes for the banana until he learns not to do so.

Eventually the cage is full of monkeys who know that they are not allowed to climb the ladder to get the banana. None of them knows why – it’s just the way it is and always has been…
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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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Through the wormhole with Stretched Clusters

Last year, EMC announced a new virtualization product called VPLEX. VPLEX allows logical storage volumes to be accessible from multiple locations. It boldly goes beyond existing storage virtualisation solutions (including those from EMC) in that it is not just a storage virtualisation cluster – but merely a storage federation platform, allowing one virtualized storage volume to be dynamically accessible from multiple locations, as if they were connected through a wormhole, and being built from one or more physical storage volumes.

Wormhole in space
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Information Lifecycle Management and Oracle databases – part 3

Archiving and purging old data

In the end, if you want to seriously reduce the effective size of a database (after using all innovations on the infrastructure level) is to move data out of the database on to something else. This is a bit against Oracle’s preferred approach as they propose to hold as much of the application data in the database for as long as possible (I wonder why…)

We could separate all archiving methods into two categories:

  • Methods that don’t change the RDBMS representation and just move tables or records to a different location in the same or different database;
  • Methods that convert database records into something else and remove it from the database layer completely

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Information Lifecycle Management and Oracle databases – part 2

Database compression

 

Compression

 

Another technique that Oracle has improved as of version 11g is compression. In versions up to 10g you could only compress an entire table, and after that, random performance on a compressed table was poor. It worked well for data warehouses where I/O bandwidth is reduced (compressed data can be read quicker from disk than uncompressed) but only in specific cases.

In 11g Oracle has introduced “advanced” compression. I will not go into details, but it allows compression on a much more granular basis, so that OLTP applications can benefit, and it works on a record-by-record basis. Oracle claims this reduces the total database size (no-brainer :) ) and therefore also the backup size (thereby ignoring the effects of tape compression that most customers use, so your mileage may vary). Data can only be compressed once, so the size of a normal database on tape compared to a compressed one will probably not be different with tape compression enabled.

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Information Lifecycle Management and Oracle databases – part 1

This is an article I wrote a while ago (late 2009), a while after EMC introduced Enterprise Flash Drives (EFD’s). Although more tooling is available these days to automate the tiering of storage, the basic concepts are still very valid, and the article might be a good explanation of the basic concept of database storage tiering and what we want to achieve with this strategy.

I recommend you read Flash Drives first to get some background knowledge before continuing with ILM.


Innovation with Flash Drives

The innovation in disk drive technology with Enterprise Flash Drives (EFD’s – also known as Solid State Disk or SSD’s) is capable of solving the problem of low random performance when using mechanical disk drives.

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Innovation with Flash Drives – part 2

Energy Efficiency of Flash

Here is a comparison of power consumption of various current drive types:

Power per Terabyte

Power per Terabyte

This picture shows the amount of energy to store 1 Terabyte of information. As this would only require one 1-Terabyte SATA drive, this is the most energy efficient (as long as you don’t need much performance). The smaller the capacity, the more drives you need to store 1 Terabyte and therefore smaller drives are less energy efficient just storing data. Faster drives (15,000 rpm) are also the most energy hungry drives so the faster the drive spins, the more energy is needed per terabyte.

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