Category: Exadata

Fully Exploiting Exadata

As a member of the Real-World Performance Group at Oracle I have participated in quite a number of Exadata POCs over the past two years. Often times those POCs are constrained in a number of ways: time, schema/app modifications, etc., because the objective is a proof, not a full blown migration. As a result there is often significant performance that is left on the table just waiting to be fully exploited — the kind of performance that really makes a database performance engineer excited — mind blowing performance. This includes, but is not limited to, data model changes, SQL query modifications and re-engineering batch processes. The reason these types of modifications get me so excited is that design decisions are often influenced by the then current deployment platform and with the Exadata powered Oracle Database Machine those restrictions are frequently lifted. You see, with Exadata the rules change, and so should your design decisions. Sure, you could just pluck-and-plop an existing Oracle data warehouse database onto an Oracle Database Machine and it would likely run much faster than it does on your current system, and you will be wowed, but you very well may shouting four letter expletives describing how fast it is if you do some re-engineering. This is why I’d like to highlight (my emphasis) this quote from a recent Pythian news update:

Pythian provides LinkShare with consulting and technical expertise for the planning, configuration, deployment, management, administration and ongoing operational support of their migration project. This includes re-engineering the database, adjusting the data model, redefining table structures, creating new indexing schemes and re-writing and tuning SQL queries, among other tasks. The project is scheduled for completion later this year and the results will be unveiled at Oracle OpenWorld in September 2010.

Hats off to both Pythian and LinkShare for realizing that they can capitalize on the opportunity to re-engineer with Exadata and fully exploit the power of the Oracle Database Machine platform. I can’t wait until Oracle OpenWorld to hear just how awesome their performance deltas are. Don’t just shoot for a level 5 performance (porting only) increase with Exadata, do a little re-engineering and turn it all the way up to 11 for that extra push over the cliff, Spinal Tap style!

Also see: Oracle Exadata worthwhile, says LinkShare

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 3.5-inch 15K RPM SAS 2.0 6Gb/sec 600GB drives. Looking at the drive spec sheet, it clearly states that the sustained sequential read is 122 MB/sec (at ID) to 204 MB/sec (at OD) [that's Inner Diameter & Outer Diameter]. Seems to me that Oracle’s claim of 1500MB/s per Exadata Storage Server (125MB/s for each of the 12 SAS drives) is certainly between 122MB/s and 204MB/s.

Now granted, one might think that vendors overstate their performance claims, so it may be resourceful to search the Internet for some third party evaluation of this hard disk. I went to a fairly well known Internet search engine to try find more information using a highly sophisticated and complex set of search keywords.  To my astonishment, there at the top of the search results page was a write up by a third party. I would encourage reading the entire article, but if you want to just skip to page 5 [Benchmarks - HD Tune Pro] you will be presented with data that shows the minimum (120MB/s), average (167MB/s) and maximum (200MB/s) read throughput for sequential read tests performed by the author for the hard disk drive in dispute. Looks to me that those numbers are completely in line with the Sun spec sheet – no over exaggeration going on here. At this point there should be exactly zero doubt that the drives themselves, with the proper SAS controller, are easily physically capable of 125MB/s read rates and more.

Stand By Or Sit Down?

Interestingly enough, after both I comment and Kevin Closson comment, calling out this ill researched assertion on the physics of HDDs, Barry Zane then responds:

As I see it, there are three possibilities:

  1. Disk vendors are overly optimistic in their continuous sequential read rates.
  2. The newer class of SAS2 compatible 15Krpm drives and controllers are faster than the older generation we’ve measured.
  3. Our disk access patterns are not getting all the available performance.

Let’s drill into each of these possibilities:

  1. Perhaps vendors are overly optimistic, but how overly optimistic could they possibly be? I mean, really, 125MB/s is easily between the spec sheet rates of 122MB/s and 204MB/s. Truly 75MB/s is a low ball number for these drives. Even Exadata V1 SAS drives more than 75MB/s per drive and the HDD is not the limiting factor in the scan throughput (a good understanding of the hardware components should lead you to what is). Even the Western Digital 300GB 10K RPM VelociRaptor disk drive has benchmarks that show a maximum sequential data transfer rate of more than 120 MB/s and sustain a minimum of 75MB/s even on the innermost part of the platter, and that is a SATA drive commonly used in PCs!
  2. Barry states that ParAccel has no experience nor metrics (measurements) with these drives or seemingly any drives like them, but yet Barry calls “75MB/sec as a conservative, reliable number”.  Just how reliable of a number can it possibly be when you have exactly zero data points and zero experience with the HDDs in dispute?  Is this a debate that can be won by strength of personality or does it actually require data, numbers and facts?
  3. Perhaps the ParAccel database has disk access patterns that can not drive the scan rates that Exadata can, but should one assert that because ParAccel database may not drive that IO rate, Exadata can’t, even when said rate is within the realm of physical capability? I certainly would think not.  Not unless the intention is simply to promote FUD.

So, as I see it, there are exactly two possibilities: Either one has technical knowledge on what they are talking about (and they have actual data/facts to support it) or they do not and they are just making things up.  At this point I think the answer is quite clear in this situation; Rick and Barry had no data to support their (incorrect) assertions.

And The Truth Shall Be Revealed

Three weeks after Barry’s “three possibilities” comment, Barry reveals the real truth:

…we [ParAccel] have gotten a number of newer servers with SAS2 drives…[and] the newer generation of disk drives are faster than my experience…Exadata’s claim of 1500MB/sec per server seems completely reasonable…My apologies for any confusion created.

As it has come to pass, my assertion that ParAccel had absolutely no experience and thus no data to support their claims is validated (not that I really had any doubts).  Spreading FUD generally does cause unnecessary confusion, but then again, that is usually the intention.  I would expect such nonsense from folks with marketing in their title, but I hold a higher bar for people with technology in their titles.  This was a simple debate about physical disk drive characteristics (and not software) and that is something anyone could get concrete factual data on (assuming they actually take the time and effort).

And Isn’t It Ironic… Don’t You Think?

The same day I read Barry’s “truth comment” I also read Jerome Pineau’s blog post on social media marketing.  I could not help but recognize (and laugh about) the irony of the situation.  Jerome lists several tips on being successful in SMM and the first two really stood out to me:

  1. Do not profess expertise on topics you know little about. Eventually, it will show.
  2. Always remain honest. Never lie. Your most important asset is credibility. You can fix almost any mistake except credibility damage.

Truly, truly ironic…

The Core Performance Fundamentals Of Oracle Data Warehousing – Introduction

At the 2009 Oracle OpenWorld Unconference back in October I lead a chalk and talk session entitled The Core Performance Fundamentals Of Oracle Data Warehousing. Since this was a chalk and talk I spared the audience any powerpoint slides but I had several people request that make it into a presentation so they could share it with others. After some thought, I decided that a series of blog posts would probably be a better way to share this information, especially since I tend to use slides as a speaking outline, not a condensed version of a white paper. This will be the first of a series of posts discussing what I consider to be the key features and technologies behind well performing Oracle data warehouses.

Introduction

As an Oracle database performance engineer who has done numerous customer data warehouse benchmarks and POCs over the past 5+ years, I’ve seen many data warehouse systems that have been plagued with problems on nearly every DBMS commonly used in data warehousing. Interestingly enough, many of these systems were facing many of the same problems. I’ve compiled a list of topics that I consider to be key features and/or technologies for Oracle data warehouses:

Core Performance Fundamental Topics

In the upcoming posts, I’ll deep dive into each one of these topics discussing why these areas are key for a well performing Oracle data warehouse. Stay tuned…

Oracle And Sun To Announce World’s First OLTP Database Machine With Sun FlashFire Technology

The internet buzz seems to be that Larry Ellison, CEO, Oracle Corporation and John Fowler, EVP, Sun Microsystems, Inc. will be announcing a new product, the world’s first OLTP database machine with Sun’s brand new FlashFire technology on Tuesday, September 15, 2009, 1 p.m. PT.

09030360_exadata_event_ers.jpg

Both Sun and Oracle have Webcast invitations on their websites:

  • Oracle Invitation
  • Sun Invitation

    I plan on being at the Oracle Conference Center for the launch and will try and Tweet the highlights. First Oracle Database 11g Release 2, now an OLTP database machine. Are there more innovations up Oracle’s sleeve? I guess we’ll have to wait and see.

  • Oracle OpenWorld 2009: The Real-World Performance Group

    Even though Oracle OpenWorld 2009 is a few months away, I thought I would take a moment to mention that the Oracle Real-World Performance Group will again be hosting three sessions. Hopefully you are no stranger to our Oracle database performance sessions and this year we have what I think will be a very exciting and enlightening session: The Terabyte Hour with the Real-World Performance Group. If you are the slightest bit interested in seeing just how fast the Oracle Database Machine really is and how it can devour flat files in no time, rip through and bend data at amazing speeds, this is the session for you. All the operations will be done live for you to observe. No smoke. No mirrors. Pure Exadata performance revealed.

    Session ID: S311237
    Session Title: Real-World Database Performance Roundtable
    Session Abstract: This session is a panel discussion including Oracle’s Real-World Performance Group and other invited performance experts. To make the hour productive, attendees need to write their questions on postcards and hand them to the panel at the beginning of the session. The questions should stick to the subject matter of real-world database performance. The panel members look forward to meeting you and answering your questions.
       
    Session ID: S311239
    Session Title: The Terabyte Hour with the Real-World Performance Group
    Session Abstract: Last year at Oracle OpenWorld, Oracle launched the Oracle Database Machine, a complete package of software, servers, and storage with the power to tackle large-scale business intelligence problems immediately and scale linearly as your data warehouse grows. In this session, Oracle’s Real-World Performance Group demonstrates how to use an Oracle Database Machine to load, transform, and query a 1-terabyte database in less than an hour. The demonstration shows techniques for exploiting full database parallelism in a simple but optimal manner.
       
    Session ID: S311238
    Session Title: Current Trends in Real-World Database Performance
    Session Abstract: The year 2009 has been an exciting one for Oracle’s Real-World Performance Group. The group has been challenged by bigger databases, new performance challenges, and now the Oracle Database Machine with Oracle Exadata Storage Server. This session focuses on some of the real-world performance ideas and solutions that have worked over the last year, including performance design philosophies, best practices, and a few tricks and tips.

    Oracle Press Release: Customers are Choosing the Oracle Database Machine

    Oracle put out a press release today entitled “Customers are Choosing the Oracle Database Machine” mentioning the new Exadata and Oracle Database Machine customers. I’ve quoted a few parts of it below. Oracle cites twenty initial customers.

    Initial Customers

    Initial Oracle Exadata customers including Amtrak, Allegro Group, Automobile Association of the UK, CTC, Garanti Bank, Giant Eagle, HISCOM (Hokuriku Coca Cola), KnowledgeBase Marketing, Loyalty Partner Solutions, M-Tel, MTN Group, Nagase, NS Solutions, NTT Data, OK Systems, Research in Motion, SoftBank Mobile, Screwfix, ThomsonReuters, and True Telecom, confirm the benefits Oracle Exadata products bring to their Oracle data warehouses.

    Supporting Quotes

  • “The HP Oracle Database Machine beat the competing solutions we tested on bandwidth, load rate, disk capacity, and transparency. In addition, Allegro Group saw a significant performance boost from the new data warehouse. A query that used to take 24 hours to complete now runs in less than 30 minutes on the HP Oracle Database Machine, and that’s without any manual query tuning.” — Christian Maar, CIO of Poznań, Poland-based Allegro Group
  • “After carefully testing various options for a new data warehouse platform we chose the HP Oracle Database Machine over Netezza. Oracle Exadata was able to speed up one of our critical processes from days to minutes. The HP Oracle Database Machine will allow us to improve service levels and expand our service offerings. We also plan to consolidate our current data warehouse solutions onto the Oracle Exadata platform. This should eliminate several servers and a number of storage arrays and help reduce our operating overhead and improve margins.” — Brian Camp, Sr. VP of Infrastructure Services, KnowledgeBase Marketing
  • “We anticipate the move of our Data Warehouse to Oracle Database 11g running on our first HP Oracle Database Machine with Oracle Exadata will deliver a substantial boost in performance and scalability, simply and easily. Our business users expect to benefit from faster access to information more quickly than ever before. The resulting agility should make a huge difference to our business.” — Andreas Berninger, Chief Operating, Loyalty Partner Solutions
  • “The biggest technological challenge we face when we architect a database is how to create a system that performs fast with huge volumes. Oracle Exadata helps solve our performance demands. It's highly available and reliable, and it can essentially scale linearly. All of the queries we tested were faster with Oracle Exadata. The smallest performance boost we experienced was 10 times; the fastest was 72 times faster.” — Plamen Zyumbyulev, Head of Database Administration, M-Tel
  • “A key component of RIM's manufacturing process is extensive testing of each handheld device. This testing generates large volumes of data, which is extensively analyzed by our quality and test engineers and business users to ensure RIM is producing the highest quality devices for our customers. The HP Oracle Database Machine is an ideal platform to store and analyze this data since it provides the performance, scalability and storage capacity for our requirements. It’s a cost-effective platform to meet our speed and scalability needs and is an integral component used for analysis in our manufacturing process.” — Ketan Parekh, Manager Database Systems, Research in Motion
  • “The benchmark result of Oracle Exadata was amazing! Since it is based on Oracle Database 11g, we determined that it is compatible with other systems and the most suitable solution for our increasing data infrastructure.” — Keiichiro Shimizu, General Manager, Business Base Management Dept., Information System Div., SoftBank Mobile Corp.
  • “Oracle Exadata is among the most successful new product introductions in Oracle's history,” said Willie Hardie, vice president of Database Product Marketing, Oracle. “Repeatedly in customer proof of concepts and benchmarks, Oracle Exadata has delivered extreme performance for customers' data warehouses.”

  • Exadata Snippits From Oracle F4Q09 Earnings Call

    Oracle Corporation had its F4Q09 earnings call today and the Exadata comments started right away with the earnings press release:

    “The Exadata Database Machine is well on its way to being the most successful new product launch in Oracle’s 30 year history,” said Oracle CEO Larry Ellison. “Several of Teradata’s largest customers are performance testing — then buying — Oracle Exadata Database Machines. In a recent competitive benchmark, a Teradata machine took over six hours to process a query that our Exadata Database Machine ran in less than 30 minutes. They bought Exadata.”

    During the earnings call Larry Ellison discusses Exadata and the competition:

    …I’m going to talk about Exadata again. I said last quarter that Exadata is shaping up to be our most exciting and successful new product introduction in Oracle’s 30 year history and [in the] last quarter Exadata continues to grow and win competitive deals in the marketplace against our three primarily competitors. It’s turning out that Teradata is our number one competitor…Netezza and IBM are kind of tied for second.

    Ellison describes some of the Exadata sales from this quarter which include:

    • A well-known California SmartPhone and computer manufacturer (win vs. Netezza) who commented that Exadata ran about 100 times faster in some cases then their standard Oracle environment
    • Research in Motion
    • Amtrak
    • A large East Coast insurance company
    • Thomson Reuters
    • A Japanese telco (biggest Teradata customer in Japan) who benchmarked Exadata and found it to be dramatically faster then Teradata
    • Barclays Capital (UK)
    • A number of banks in Western Europe and Germany

    Larry Ellison follows with:

    It was just a great quarter for Exadata, a product that is relatively new to the marketplace that is persuading people to move from their existing environments because Exadata is faster and the hardware costs less.

    In the Q&A Larry Ellison responds to John DiFucci on Exadata:

    By the way every customer I mentioned and alluded to were actual sales. Now some of these, because the Exadata product is so new, quite often will install in kind of a try and buy situation, but I can’t think of a case where we installed the machine that they didn’t buy. So we’re winning these benchmarks. Sometimes we’re beating Teradata. I think in my quote, I said we’ve beat Teradata on one of the queries by 20 to one. So we think it’s a brand new technology, we think we’re a lot faster then the competition. The benchmarks are proving out with real customer data, we’re proving to be much faster then the competition. Every single deal I mentioned were cases where the customer bought the system. There are obviously other evaluations going on and we expect the Exadata sales to accelerate.

    Oracle And HP Take Back #1 Spot For 1TB TPC-H Benchmark

    Oracle and HP have taken back the #1 spot by setting a new performance record in the 1TB TPC-H benchmark. The HP/Oracle result puts the Oracle database ahead of both the Exasol (currently #2 & #3) and ParAccel (currently #4) results in the race for performance at the 1TB scale factor and places Oracle in the >1 million queries per hour (QphH) club, which is no small achievement. Compared to the next best result from HP/Oracle (currently #5), this result has over 9X the query throughput (1,166,976 QphH vs. 123,323 QphH) at around 1/4 the cost (5.42 USD vs. 20.54 USD) demonstrating significantly more performance for the money.

    Some of the interesting bits from the hardware side:

    • 4 HP BladeSystem c7000 Enclosures
    • 64 HP ProLiant BL460c Servers
    • 128 Quad-Core Intel Xeon X5450 “Harpertown” Processors (512 cores)
    • 2TB Total System Memory (RAM)
    • 6 HP Oracle Exadata Storage Servers

    As you can see, this was a 64 node Oracle Real Application Cluster (RAC), each node having 2 processors (8 cores). This is also the first TPC-H benchmark from Oracle that used Exadata as the storage platform.

    Congratulation to the HP/Oracle team on the great accomplishment!

    Transaction Processing Performance Council_1244094205417.png

    Larry Ellison Mentions Exadata Performance Numbers

    Yesterday Oracle Corporation had its earnings call for F3Q2009. On the call Larry and Charles mention a few of the Exadata performance numbers observed.

    Larry Ellison:

    …looking forward, I think the most exciting product we’ve had in many, many years is our Exadata Database Server…

    Exadata is 100% innovation on top of our very large and very strong database business. And the early results have been remarkable. Charles Phillips will go into a lot of detail but I’ll just throw a couple of numbers out there.

    One of our customers, and Charles will describe this customer, one of our customers saw a 28x performance improvement over an existing Oracle database. Another customer saw a monthly aggregation drop from 4.5 hours just to 3 minutes.

    When compared to Teradata, a competitive database machine that’s been in the market for a very, very long time, another customer saw that we were 6x faster than their existing Teradata application, when using Exadata versus Teradata.

    Another customer saw a batch process fall from 8 hours to 30 minutes. Charles will go into more detail on all this, he will repeat those numbers, because I think they’re worth mentioning twice.

    Charles Phillips:

    On databases, Larry mentioned, we’re very excited about how the HP Oracle database machine is performing. The increases have just been stunning and so we are getting great feedback from our customers and the pipeline is the largest build I’ve ever seen in terms of a new product.

    And as he mentioned, the numbers are just stunning. The major European retailer who reduced the batch processing time from 8 hours to 30 minutes did not believe the process had completed. We had to convince him that’s actually how it’s done.

    And so, as Larry mentioned, this is the reminder that this is an internally developed technology in the midst of all the discussion of acquisitions. People forget that we’re actually spending $3.0 billion a year on research and development and this is why we do it.

    I agree with Larry 100%. Exadata is the most exciting product and from a database performance engineer perspective (and a hardware junkie) it is quite amazing to see a single 42U rack of HP Oracle Database Machine rip and tear through terabytes of data as if it were breaking the laws of physics. Quite exciting indeed.

    Oracle Exadata: In Response to Chuck Hollis

    Chuck Hollis, VP and Global Marketing CTO at EMC has written a couple blog posts offering his thoughts on Oracle Exadata. The first was “Oracle Does Hardware” which he wrote the day after the product launch. The second, unimpressively titled “I Annoy Kevin Closson at Oracle” was on Monday October 20th which was in response to a blog post by Exadata Performance Architect, Kevin Closson who commented on Chuck’s first post and some comments left on Kevin’s blog.

    Clearly Stated Intentions

    Since Chuck had disabled comments for his “I Annoy Kevin” post, I’m going to write my comments here. I have no intention to get into some fact-less debate turn flame, but I will make some direct comments with supporting facts and numbers while keeping it professional.

    Storage Arrays: Bottleneck or Not?

    Chuck thinks:

    “…array-based storage technology is not the bottleneck; our work with Oracle [on the Oracle Optimized Warehouse Initiative] and other DW/BI environments routinely shows that we can feed data to a server just as fast as it can take it.”

    First let me comment on the Optimized Warehouse Initiative. There have been some good things that have come out of this effort. I believe it has increased the level of awareness when it comes to sizing storage for BI/DW workloads. All too often storage sizing for BI/DW is done by capacity, not I/O bandwidth. The focus is on building balanced systems: systems that can execute queries and workloads such that no one component (CPU/storage connectivity/disk array/disk drives) becomes the bottleneck prematurely. The industry seems to agree: IBM has the Balanced Warehouse and Microsoft has a reference architecture for Project Madison as well.

    So the question comes back to: Is array-based storage technology the bottleneck or not? I would argue it is. Perhaps I would use a word other than “bottleneck”, but let’s be clear on the overall challenge here. That is: to read data off disk with speed and efficiently return it to the database host to process it as fast as possible.

    Let’s start at the bottom of the stack: hard disk drives. If the challenge is to scan lots of data fast, then how fast data can be read off disk is the first important metric to consider. In the white paper Deploying EMC CLARiiON CX4-960 for Data Warehouse/Decision Support System (DSS) Workloads EMC reports a drive scan rate (for a BI/DW workload) of 20 MB/s using 8+1 RAID-5 and 33 MB/s using a 2+1 RAID-5 LUN configuration. Oracle Exadata delivers drive scan rates around 85 MB/s, a difference of 2.5X to 4.25X. To understand the performance impact of this I’ve put together a few tables of data based on these real workload numbers.

    Hardware Specs and Numbers for Data Warehouse Workloads

    Storage RAID Raw:Usable Ratio Disk Drives Disk Scan Rate
    EMC CX4-960
    8+1 RAID 5
    9:8
    146 GB FC 15k RPM
    20 MB/s
    EMC CX4-960
    2+1 RAID 5
    3:2
    146 GB FC 15k RPM
    33 MB/s
    EMC CX4-960
    8+1 RAID 5
    9:8
    300 GB FC 15k RPM
    20 MB/s
    EMC CX4-960
    2+1 RAID 5
    3:2
    300 GB FC 15k RPM
    33 MB/s
    Oracle Exadata
    ASM Mirroring
    2:1
    450 GB SAS 15k RPM
    85 MB/s

    Sizing By Capacity

    Storage RAID Total Usable Space Disk Drive Number of Drives Total Scan Rate
    EMC CX4-960
    8+1 RAID 5
    18 TB
    146 GB
    139
    2.8 GB/s
    EMC CX4-960
    2+1 RAID 5
    18 TB
    146 GB
    185
    6.1 GB/s*
    EMC CX4-960
    8+1 RAID 5
    18 TB
    300 GB
    68
    1.4 GB/s
    EMC CX4-960
    2+1 RAID 5
    18 TB
    300 GB
    90
    3.0 GB/s
    Oracle Exadata
    ASM Mirroring
    18 TB
    450 GB
    80
    6.8 GB/s

    * I’m not sure that the CX4-960 array head is capable of 6.1 GB/s so it likley takes at least 2 CX4-960 array heads to deliver this throughput to the host(s).

    Sizing By Scan Rate

    Storage RAID Total Scan Rate Disk Drive Number of Drives Total Usable Space
    EMC CX4-960
    8+1 RAID 5
    3.00 GB/s
    146 GB
    150
    19.46 TB
    EMC CX4-960
    2+1 RAID 5
    3.00 GB/s
    146 GB
    90
    8.76 TB
    EMC CX4-960
    8+1 RAID 5
    3.00 GB/s
    300 GB
    150
    40.00 TB
    EMC CX4-960
    2+1 RAID 5
    3.00 GB/s
    300 GB
    90
    18.00 TB
    Oracle Exadata
    ASM Mirroring
    3.00 GB/s
    450 GB
    36
    8.10 TB

    A Few Comments On The Above Data Points

    Please note that “Total Usable Space” is a rough number for the total protected disk space one can use for a database if you filled each drive up to capacity. It does not take into consideration things like loss for formatting, space for sort/temp, etc, etc. I would use a 60% rule for estimating data space for database vs. total usable space. This means that 18 TB of total usable space would equate to 10 TB (max) of space for database data (compression not accounted for).

    I’d also like to note that in the Sizing By Capacity table the “Total Scan Rate” is a disk only calculation. Whether or not a single CX4-960 array head can move data at that rate is in question. Based on the numbers in the EMC whitepaper it would appear CX4-960 head is capable of 3 GB/s but I would question if it is capable of much more than that, hence the reason for the asterisk(*).

    Looking At The Numbers

    If you look at the number for Sizing By Capacity, you can see that for the given fixed size, Exadata provides the fastest scan rate while using only 80 disk drives. The next closest scan rate is just 700 MB/s less but it uses 105 more disk drives (80 vs. 185). Quite a big difference.

    When it comes to delivering I/O bandwidth, Exadata clearly stands out. Targeting a scan rate of 3 GB/s, Exadata delivers this using only 36 drives, just 3 Exadata Storage Servers. If one wanted to deliver this scan rate with the CX4 it would take 2.5X as many drives (90 vs. 36) using 2+1 RAID 5.

    So are storage arrays the bottleneck? You can draw your own conclusions, but I think the numbers speak to the performance advantage with Oracle Exadata when it comes to delivering I/O bandwidth and fast scan rates. Consider this: What would the storage topology look like if you wanted to deliver a scan rate of 74 GB/s as we did for Oracle OpenWorld with 84 HP Oracle Exadata Storage Servers (6 HP Oracle Database Machines)? Honestly I would struggle to think where I would put the 185 or so 4Gb HBAs to achieve that.

    Space Saving RAID or Wasteful Mirroring

    This leads me to another comment by Chuck in his second post:

    “[with Exadata] The disk is mirrored, no support of any space-saving RAID options — strange, for such a large machine”

    And this one in his first post:

    “If it were me, I’d want a RAID 5 (or 6) option.”

    And his comment on Kevin’s blog:

    “The fixed ratio of 12 disks (6 usable) per server element strikes us as a bit wasteful….And, I know this only matters to storage people, but there’s the minor matter of having two copies of everything, rather than the more efficient parity RAID approaches. Gets your attention when you’re talking 10-40TB usable, it does.”

    Currently Exadata uses ASM mirroring for fault tolerance so there is a 2:1 ratio of raw disk to usable disk, however I don’t think it matters much. The logic behind that comment is that when one is sizing for a given scan rate, Exadata uses less spindles than the other configurations even though the disk protection is mirroring and not space-saving RAID 5. I guess I think it is strange to worry about space savings when disks just keep getting bigger and many are keeping the same performance characteristics as their predecessors. Space is cheap. Spindles are expensive. When one builds a configuration that satisfies the I/O scan rate requirement, chances are you have well exceeded the storage capacity requirement, even when using mirroring.

    Perhaps Chuck likes space-saving RAID 5, but I think using less drives (0.4 as many, 36 vs. 90) to deliver the same scan rate is hardly wasteful. You know what really gets my attention? Having 40 TB of total usable space on 15 HP Oracle Exadata Storage Servers (180 450GB SAS drives) and being able to scan it at 15 GB/s compared to say having a CX4 with 200 drives @ 300GB using 2+1 R5 and only being able to scan them at 6.6 GB/s. I’d also be willing to bet that would require at least 2 if not 3 CX4-960 array heads and at least 30 4Gb HBAs running at wire speed (400 MB/s).

    Exadata Is Smart Storage

    Chuck comments:

    “Leaving hardware issues aside, how much of the software functionality shown here is available on generic servers, operating systems and storage that Oracle supports today? I was under the impression that most of this great stuff was native to Oracle products, and not a function of specific tin …

    If the Exadata product has unique and/or specialized Oracle logic, well, that’s a different case.”

    After reading that I would said Chuck has not read the Technical Overview of the HP Oracle Exadata Storage Server. Not only does Exadata have a very fast scan rate, it has intelligence. A combination of brawn and brains which is not available with other storage platforms. The Oracle Exadata Storage Server Software (say that 5 times fast!!!) is not an Oracle database. It is storage software not database software. The intelligence and specialized logic is that Exadata Smart Scans return only the relevant rows and columns of a query, allowing for better use of I/O bandwidth and increased database performance because the database host(s) are not issuing I/O requests for data that is not needed for the query and then processing it post-fact. There are a couple slides (18 & 19) referencing a simple example of the benifits of Smart Scans in the HP Oracle Exadata Storage Server technical overview slide deck. It is worth the read.

    It Will Be Interesting Indeed

    Chuck concludes his second post with:

    “The real focus here should be software, not hardware.”

    Personally I think the focus should be on solutions that perform and scale and I think the HP Oracle Exadata Storage Server is a great solution for Oracle data warehouses that require large amounts of I/O bandwidth.

    Ending On A Good Note

    While many comments by Chuck do not seem to be well researched I would comment that having a conventional mid-range storage array that can deliver 3 GB/s is not a bad thing at all. I’ve seen many Oracle customers that have only a fraction of that and there are probably some small data warehouses out there that may run fine with 3 GB/s of I/O bandwidth. However, I think that those would run even faster with Oracle Exadata and I’ve never had a customer complain about queries running too fast.