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Exadata

“Flash” Storage Will Be Cheap – The End of the World is Nigh

A couple of weeks ago I tweeted a projection that the $/GB for flash drives will meet the $/GB for hard drives within 3-4 years. It was more of a feeling based upon current pricing with Moore’s Law applied than a well researched statement, but it felt about right. I’ve since been thinking some more [...]

Oracle Exadata Delivery Day

Well our new Exadata showed up this week. We had a pretty nice lab environment already. A bunch of Dell’s, some IBM’s, several Sun’s. We have a couple of EMC Sans as well (we actually threw away a whole EMC rack to make room for the Exadata). And of course we have every version of Oracle from 8i to 11gR2. It’s a good learning environment. It also let’s us try things when clients have a specific set of versions that we want to mimic. So now we have an Exadata V2 as well. We’ve had the delivery date on the calendar for several weeks. For some reason it reminded of the Weird Al Yankovik song Weasel Stomping Day.

How Good Are the Values Returned by DBMS_COMPRESSION.GET_COMPRESSION_RATIO?

According to the documentation the GET_COMPRESSION_RATIO procedure of the DBMS_COMPRESSION package can be used to assess the impact of different compression options for a given table. In other words, it allows us to find out the expected compression ratio for a given set of data without having to really create a compressed table. The question [...]

Oracle Exadata V2 - Flash Cache

One of the things I didn’t really talk about in my first post on Exadata was the flash cache component of the storage servers. They are a key component of the “OLTP” claims that Oracle is making for the platform. So let’s talk about the hardware first. The storage servers have 4 of the Sun Flash Accelerator F20 PCIe cards. These cards hold 96G each for a total of 384G on each storage server. That’s well over a terabyte on the smallest quarter rack configuration. Here’s what they look like:

Note that they are only installed in the storage servers and not in the database servers. The cards are usually configured exclusively as Flash Cache, but can optionally have a portion defined as a “ram disk”.

Oracle has a White Paper here:

Exadata Smart Flash Cache and the Sun Oracle Database Machine

This white paper was published in late 2009 and it is specific to V2. It has some good information and is well worth reading. One of the comments I found interesting was the discussion of carving a piece of the Flash Cache out as a “disk”. Here’s the quote:

Filter Early

Yesterday, my 12 year-old son Alex was excited to tell me that he had learned a new trick that made it easier to multiply fractions. Here’s the trick:

Exadata Storage Server and the Query Optimizer – Part 3

In the first and second post of this series I shared with you some basics about smart scan and gave some details about projection and restriction. The aim of this post is to cover the third basic technique: join filtering.
Join filtering is not something specific to the Exadata Storage Server. In fact, it is an [...]

Exadata Storage Server and the Query Optimizer – Part 2

In the first post of this series I shared with you some basics about smart scan and gave some details about projection. The aim of this post is to cover the second basic technique: restriction. Simply put, the aim of this technique is to offload to a cell the processing of predicates found in the [...]

Exadata Storage Server and the Query Optimizer – Part 1

Even though the utilization of an Exadata Storage Server should be transparent for the query optimizer, when you look at execution plans generated in an environment using it you might notice slight differences. The purpose of this series of post is to summarize the differences I was able to observe.
Disclaimer: I do not have access [...]

Fun with Oracle Exadata V2

Well I’ve been holed up playing with an Exadata V2 machine for the past several weeks. Wow. Very interesting technology.

I must say that I believe the concept of offloading SQL processing to the storage layer is a game changer and I wouldn’t be at all surprised to see this as a standard feature a few years from now. What that means for other storage vendors is unclear at this point. So for this first post on the topic let me just describe the configuration (and some potential upgrades).

The basic architecture consists of a set of database severs and a set of storage servers.

Database Servers:

  • Sun x4170 (1RU 64x server)
  • 2 - Quad-core Intel Xeon E5540 2.53GHz processors
  • 72G Ram (18×4G Dimms - max of 144G using 8G DIMMs)
  • Dual-Port QDR InfiniBand Host Channel Adapter
  • HBA with 512MB Battery Backed Write Cache (only for internal disks???)
  • 4 - 146G internal drives (SAS 10,000 RPM)
  • dual hot swappable power supplies
  • no spare/empty slots!

Here’s what the Database Servers look like:

Storage Servers:

  • Sun x4275 (2RU 64x server)
  • 2 - Quad-core Intel Xeon E5540 (2.53GHz) processors
  • 24G Ram
  • Dual-Port QDR InfiniBand Host Channel Adapter
  • HBA with 512MB Battery Backed Write Cache (only for internal disks???)
  • dual hot swappable power supplies
  • 4 - 96G Sun Flash PCIe Cards (total of 384 GB)
  • 12 - 600 GB 15,000 RPM SAS or 2 TB 7,200 RPM SATA


Here’s what the Storage Servers look like:

Partway Researched With A Chance Of FUD

I tend to keep the content of this blog fairly technical and engineering focused, but every now and then I have to venture off and do an editorial post.  Recently some of the ParAccel management decided to fire up the FUD machine on the ParAccel blog and take aim at Oracle’s Exadata making the following claims: “There are 12 SAS disks in the storage server with a speed of about 75 MB/s [The SUN Oracle Exadata Storage Server datasheet claims 125 MB/s but we think that is far-fetched.]” -Rick Glick, Vice President of Technology and Architecture (link) “We stand by the 75MB/sec as a conservative, reliable number. We see higher numbers in disk tests, but never anywhere near 125MB/sec.” -Barry Zane, Chief Technology Officer (link) Far Fetched Or Fact? As a database performance engineer, I strive to be extremely detailed and well researched with my work. Clearly, these comments from Rick and Barry were not well researched as is evident from information publicly available on the Internet. The first bit of documentation I would research before making such comments would be the hard disk drive specification sheet. The 12 drives in the Exadata Storage Server, a Sun Fire X4275, are [...]