The Enkitec Extreme Exadata Expo is well underway having just brought day 1 to a close with a keynote from Oracle’s Senior Vice President of Database Server Technology, Andy Mendelsohn.
Mr. Mendelson ended his presentation with a slide of futures for Exadata. Frits Hoogland tweeted the slide here.
I too was listening in on the presentation as a virtual attendee. I heard Mr. Mendelsohn state that the features fall into the “within 12 months” category. I suppose that means coinciding with Oracle Database 12.2 (note, dot-2). I could certainly be wrong on that matter though. Perhaps 12.1. We’ll see.
Of the items on the list I’d say the most interesting was the “Flash for all writes” item. The bullet point is enhanced with a pledge of 10x more writes for write-heavy OLTP. I knew of this feature and its eventual release, but now the information is public.
As my many posts on the matter attest, I have been critical of Oracle referring to Exadata as the “World’s First OLTP Machine” simply because it has read-cache. OLTP requires the scaling of writes along with reads. However, according to Oracle’s Exadata datasheets, the “World’s First OLTP Machine” is currently capable of 1.5 million read IOPS in a full-rack X2 configuration but only 50,000 gross random writes. With normal ASM redundancy the gross is reduced to a net WIOPS capacity of approximately 25,000 or a read:write ratio of 60:1. Many users feel compelled to use ASM high redundancy for reasons outside the scope of this post.
An increase in 10x would be 500,000 WIOPS (gross) which, being a write-back cache, will have to be de-staged back to spinning media at some point.
It will be interesting to see how this feature plays out. On first glance it would appear as though the goal is to support a read:write ratio of 6:1 which is drastically better than the World’s First OLTP Machine. If the World’s Second OLTP Machine can handle the de-staging from cache back to spinning media I’ll say kudos. Until we know, we can only guess.
Personally, I’m putting my bets on completely non-mechanical approaches for solving write-intensive OLTP problems. That’s another way of saying total flash storage. However, I’d also stack up auto-tiering (e.g., EMC FAST) against this approach because the de-staging requirement is reduced as blocks are promoted to Enterprise Flash Drives. I have not performed any benchmark to back that viewpoint…but then I suspect a feature intended to see light of day “within 12 months” is getting much benchmark action within Oracle development either. There again, I could be wrong because I no longer work there.
What Are People Buying This Stuff For?
Since the vast majority of Exadata sales are quarter-rack configurations deployed for applications other than Data Warehousing I think Oracle is focusing on the correct weaknesses.
If you’re interested, I spoke of closely related topics in my recent interview in the August edition of the Northern California Oracle User Groups journal.
Finally, if you haven’t seen my video presentations on the fundamental architectural reasons Exadata is inferior to other solutions in the marketplace for the DW/BI/Analytics use case, I recommend you give them a viewing. Doing so might help you understand why Oracle sells more Exadata for use cases other than DW/BI and, in turn, why they focus on features that have nothing to do with that use case–like write-back flash cache.
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