SAPonPower

An ongoing discussion about SAP infrastructure

Haswell-EX for HANA looks good on paper, POWER8 for HANA looks even better in real life

I was delighted to read Hasso Plattner’s recent blog on the strengths of HANA on platforms using the Haswell-EX chip from Intel:  https://blogs.saphana.com/2015/06/29/impact-of-haswell-on-hana/  In that blog, he did an excellent job of explaining how technical enhancements at a processor and memory subsystem level can result in dramatic improvement in the way that HANA operates,   Now, I know what you are thinking; he likes what Dr. Plattner has to say about a competitor’s technology?   Strange as it may seem, yes … in that he has pointed out a number of relevant features that, as good as Haswell-EX might be, POWER8 surpassed, even before Haswell-EX was announced.

All of these technical features and discussion are quite interesting to us propeller heads.   Most business people, on the other hand, would probably prefer to discuss how to improve HANA operational characteristics, deliver flexibility to respond to changing business demands and meet end user SLAs including response time and continuous availability.  This is where POWER8 really shines.  With PowerVM at its core, Power Systems can be tailored to deliver capacity for HANA production to ensure consistent response time and peak load capacity during high demand times and allow other applications and partitions to utilize capacity unused by the HANA production partition.   It can easily mix production with other production and non-production partitions.  It features the ability to utilize shared network and SAN resources, if desired, to reduce datacenter cost and complexity.  POWER8 delivers unmatched reliability by default, not as an option or a tradeoff against performance.

Regarding the technical features, Herr Dr. Plattner points out that Haswell-EX systems:

  • Support up to 144 cores per system with 12TB of memory.  POWER8 supports up to 196 cores and 16TB.  Actually, this under estimates that actual memory on a POWER8 system which is actually up to 17.7TB but IBM includes the extra 1.7TB at no extra cost as hot spare chips, not available with Haswell-EX systems.
  • Deliver L1, L2 and L3 cache size increases, which though he does not state, are, in fact, 32KB (16KB in enterprise RAS mode), 256KB and 45MB respectively, compared to POWER8’s 64KB, 512KB and 96MB respectively plus 128MB L4, not available with Haswell-EX systems.
  • Introduces enhancements to vector processing via the new AVX2 instruction unit compared to  POWER8’s dual VMX instruction units.
  • Rely on local memory access for HANA performance which is absolutely true and underlines why POWER8, with up to 4 times more bandwidth to memory, is such a good fit for HANA.
  • Feature TSX, Transactional Synchronization Extensions, to improve lock synchronization, an area that Power Systems has excelled at for decades.  POWER8 was actually a bit earlier in the whole transactional memory area but was actually preceded by IBM Blue Gene/Q, another PowerPC based technology.

He concludes by pointing out that internal benchmarks are of limited value but then explains what they achieved with Haswell-EX.  As these are not externally audited nor even published, it is hard to comment on their validity.

By comparison, SAP has only one certified benchmark for which HANA systems have been utilized called BW-EML.  Haswell-EX cpus were used in the 2B row Dell PowerEdge 930 benchmark and delivered an impressive 172,450 Ad-hoc Navigation Steps/Hr . This is impressive in that it surpassed the previous IvyBridge based benchmark of 137,010 Ad-hoc Navigation Steps/Hr on the Dell PowerEdge R920, an increase of almost 26% which would normally be impressive if it weren’t for the fact that the system includes 20% more cores and 50% more memory.  By comparison, POWER8 delivered 192,750 Ad-hoc Navigation Steps/Hr with the IBM Power Enterprise System 870 or 12% more performance with 45% fewer cores and 33% less memory resulting in twice the performance per core.

It would be ideal to run the SAP SD 3-tier benchmark against a system running Suite on HANA as that would do away with discussions of benchmarks that can’t be verified and/or may have limited relevance to a transactional environment typical of Suite on HANA.  From what I understand, the current SD benchmark depends on an older version of SAP code which is not supported on HANA.  I hope that SAP is able to update the benchmark test kit to enable this benchmark to be run on HANA as that would be far better than any sort of speculation.  In the meantime, we can only rely on assertions without detail and external review or on decades of proven experience handling large scaling transactional environments with mission critical levels of availability not to mention a wide variety of audited benchmarks demonstrating this ability.  Power Systems stands alone in this respect.

Benchmark details:

Dell PowerEdge 930: 172,450 Ad-hoc Navigation Steps/Hr using 4 processors / 72 cores / 144 threads, Intel Xeon Processor E7-8890 v3, 2.50 GHz, 1.5TB main memory, Certification #: 2015014

Dell PowerEdge R920: 137,010 Ad-hoc Navigation Steps/Hr on the, 4 processors / 60 cores / 120 threads, Intel Xeon Processor E7-4890 v2, 2.80 GHz,  1TB main memory, Certification #: 2014044

the IBM Power Enterprise System 870: 192,750 Ad-hoc Navigation Steps/Hr with, 4 processors / 40 cores / 320 threads, POWER8, 4.19 GHz,  1TB main memory, Certification #: 2015024

Advertisements

July 22, 2015 - Posted by | Uncategorized | , , , , , , , , , , ,

No comments yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: