In my recent blog entry entitled “Oracle Exadata Storage Server. No Magic in an Imperfect World. Excellent Tools and Really Fast I/O Though“, I concluded with a reference to some anti-Exadata comments made by EMC’s Chuck Hollis in his blog entry entitled “Oracle Does Hardware.” I directed my readers to that blog post by writing the following:
In spite of how many times EMC’s Chuck Hollis may claim that there is “nothing new” or “no magic” when referring to Oracle Exadata Storage Server, I think it is painfully obvious that there is indeed “something new” here. Is it magic? No, and we don’t claim that it’s magic.
Six days after I posted that blog entry, Chuck submitted a lengthy comment on the post. Instead of responding to Chuck’s comments in the comment thread I’ve decided to do so here.
Readers please don’t confuse this as some sort of Kevin versus Chuck thread because it isn’t. What you’ll see in this post is an analysis of the words of someone representing one of the (if not the premier) conventional storage providers (EMC). My motives are to provide useful information in this analysis.
If you read Chuck’s assessment of Oracle Exadata Storage Server, you’ll see a positioning piece with an overtly anti-Exadata slant. Chuck’s words in that post are aimed at conveying facts. My first handling of that anti-Exadata piece was very light. I aimed to capitalize foremost on the repetitious use of the words “nothing new” and “magic.” Chuck likely saw my post where I called this out. Chuck answered my calling-out in the comment thread of this post. Chock wrote:
Sorry, Kevin, didn’t mean to come across as too pessimistic in my blog.
I need to point out that one cannot be pessimistic about facts. The word pessimistic only applies to beliefs and emotions. Chuck’s piece wasn’t pessimistic–it was flawed based on technical grounds. Chuck continued with:
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 …
Last Chance for a First Impression
Chuck’s “pessimistic” post came out the day after the Oracle Exadata Storage Server launch so harboring such questions in his mind at that time would have been understandable. However, Chuck visited my blog some 22 days later and continued to ask questions that clearly demonstrate a lack of understanding of Oracle Exadata Storage Server. Chuck may have been “under the impression” that the underpinnings of Exadata are Oracle-generic (“native to Oracle products”), but he is wrong. Oracle Exadata Storage Server software is not a scalpel-job on the Oracle Database server. It is a totally new storage server software package.
To answer Chuck’s question about the software, none of the software functionality (Exadata) is available on generic servers, operations systems or storage. Chuck continued with:
If the Exadata product has unique and/or specialized Oracle logic, well, that’s a different case.
Yes, it is unique and specialized and a different case. Even light reading of the available material (e.g., the Exadata paper and, shucks, maybe a few of my blog posts) would have made that glaringly obvious. Chuck continued with:
Speaking strictly as a storage guy, here’s what I know.
- using commodity servers and storage arrays, we can usually feed in more data than a server can process, specifically true in an Oracle DW environment.
Chuck, swamping a commodity server is not the goal. Of course it’s easy to produce more raw, streaming data from even a midrange storage array than can be ingested by a single commodity server. Even the best commodity servers choke at less than 2GB/s data ingest rate when Oracle is performing data-rich functionality (e.g., joins, sorts, aggregation, etc). The design goal of Exadata was not to swamp commodity servers more efficiently. That would be a storage-only, bigger hose, speed-and-feed mentality-the “brute force only approach.”
You Don’t Always Get What You Want-Enter Exadata
The value proposition of Exadata is to scan disk without bottlenecks and return to the Database grid only the data the query wants, not blocks of disk. It’s a feature we call Smart Scan. Chuck needs to have his folks brief him on that. However, Exadata is more than capable of holding its own in the pure “brute force” camp.
Even Without Smart Scan, Exadata is Faster Than Conventional Storage
As a simple block server, Exadata is able to deliver 1GB/s per cell to the Database grid. If you don’t think that is “brute force”, consider a moderate Oracle Database Machine configuration consisting of a single rack serving 14 GB/s to the Database grid. If those numbers don’t speak loudly enough, just investigate what sort of conventional SAN array configuration it would take to deliver 14 GB/s to a Database grid. So, yes, Exadata is both “brute force” and intelligent and that is why I had to call out Chuck’s blog remarks about how Exadata is “nothing new.”
Chuck finished that paragraph with:
I’m having a hard time seeing the advantages of pairing a commodity Xeon-based server with JBOD and claiming a performance advantage for this part of the equation.
Oh my, where to start. Chuck, I understand why you would have difficulty seeing the advantage in what you just described, but what on earth does any of that have to do with Oracle Exadata Storage Server? First, where did you get “JBOD?” An Oracle Exadata Storage Server cell is not just a Xeon processor sitting in front of some disks (JBOD). The disks are down-wind of an intelligent HP P400 Smart Array with 512MB battery-backed write cache. And, what’s so terrible about fronting some disks with Xeon technology anyway? There are a few conventional storage arrays on the market that use Xeon in the array head.
It’s All About Balance
Fingering the fact that Intel Xeon processors execute storage intelligence software in the Oracle Exadata Storage Server doesn’t hold water–especially since the ratio is 2 sockets per 12 hard drives. Perhaps Chuck will tell us the maximum number of Xeon processors EMC supports in front of 960 drives in a fully loaded midrange EMC array (e.g., CX)?
Oracle has purpose-built a balanced system by coupling the power of 2 Xeon processors (Harpertown quad-core) in front of 12 drives.
Infiniband: The Exadata “Secret Sauce?”
Chuck continued with:
- you may be more knowledgeable than I, but we are under the impression that the IB compute node connection doesn’t bring much to the party. When we looked at many clustered Oracle DW implementations, there was plenty of bandwidth available between the compute nodes, using multiple 1Gb/sec links.
That’s why we don’t talk about it much. Infiniband is not why Exadata is so fast. Infiniband is one of the reasons why Exadata is not bottlenecked. First, I’ll point out that Infiniband is a unified fabric for both disk and inter-node communications with Exadata. I’ve been writing about storage up to this point and now the focus is shifted to Real Application Clusters (RAC) interconnect technology. I’ll be brief on this topic. I don’t doubt, nor do I care, that there are clustered Oracle DW systems currently deployed that are able to get by with multiple UDP Gigabit Ethernet networks configured as the RAC interconnect. That’s just fine with me. Does that somehow negate the value of Exadata because Oracle so foolhardy engineered a zero-copy RDMA interconnect for RAC while unifying interconnect and storage networking into a single fabric? I shouldn’t think so. UDP costs some (lots) of cycles compared to ZDP over Infiniband. Just because a network has headroom left over doesn’t mean resources are otherwise being utilized efficiently. Oracle didn’t aim to engineer bottlenecks into the Exadata architecture.
Chuck continued with:
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.
Yes, the initial release of Exadata requires 1:1 mirroring. Does that somehow insinuate that Exadata will never offer the more space-saving RAID approached Chuck is alluding to? Life is, after all, an unending series of choices.
Everyone Includes EMC
Chuck continued with:
Bottom line – what does the hardware bring to the party, rather than software? And if you can get the same benefits without dictating that customers buy a specific piece of tin, isn’t that a win for everyone?
Chuck, and my blog readers alike, should know by now what the hardware brings to the party. Oracle Exadata Storage Server hardware is-unlike conventional storage arrays-not configured with guaranteed throughput bottlenecks built in. That warrants a party. On the other hand, the software is the secret sauce. The choice of which “tin” gets to run the software is, of course, someone else’s decision. I will say, however, if you were to execute the software on systems less balanced than the current platform (HP Proliant DL180 G5), you would not realize the benefit. It’s all about balance.
Chuck finished with:
Finally, I’d be interested in your thoughts on how enterprise flash drives fit into all of this. Yes, they’re rather expensive now, but this won’t be the case before too long.
I’ve bored you all to death already. I’ll hit FLASH SSD in my next blog entry.