SAPonPower

An ongoing discussion about SAP infrastructure

Lintel for SAP App Servers – The right choice

Or is it? Running SAP application servers on IBM Power Systems with Linux results in a lower TCA than using x86 systems with Linux and VMware. Usually, I don’t start a blog post with the conclusion, but was so amazed by the results of this analysis, that I could not help myself.

For several years now, I have seen many customers move older legacy app servers to x86 systems using Linux and VMware as well as implementing new SAP app servers on the same. When asked why, the answers boil down to cost, skills and standards. Historically, Lintel servers were not just perceived to cost less, but could the cost differences could be easily demonstrated. Students emerging from colleges have worked with Linux far more often than with UNIX and despite the fact that learning UNIX and how it is implemented in actual production environments is very little different in real effort/cost, the perception of Linux skills being more plentiful and consequently less expensive persists. Many companies and government entities have decided to standardize on Linux. For some legacy IBM Power Systems customers, a complicating factor, or perhaps a compelling factor in the analysis, has compared partitions on large enterprise class systems against low cost 2-socket x86 servers. And so, increasingly, enterprises have defaulted to Lintel as the app server of choice.

Something has changed however and is completely overturning the conventional wisdom discussed above. There is a new technology which takes advantage of all of those Linux skills on the market, obeys the Linux standards mandate and costs less than virtualized Lintel systems. What is this amazing new technology? Surprise, it is a descendent of the technology introduced in 1990 by IBM called the RS/6000, with new Linux only POWER8 systems. (OK, since you know that I am an IBM Power guy and I gave away the conclusion at the start of this post, that was probably not much of a surprise.) At least, this is what the marketing guys have been telling us and they have some impressive consultant studies and internal analyses that back up their claims.

For those of you who have been following this blog for a while, you know that I am skeptical of consultant analyses and even more so of internal analyses. So, instead of depending on those, I set out to prove, or disprove, this assertion. The journey began with setting reasonable assumptions. Actually, I went a little overboard and gave every benefit of the doubt to x86 and did the opposite for Power.

Overhead – The pundits, both internal and external, seem to suggest that 10% or more overhead for VMware is reasonable. Even VMware’s best practices guide for HANA suggests an overhead of 10%. However, I have heard some customers claim that 5% is possible. So, I decided to use the most favorable number and settled on 5% overhead. PowerVM does have overhead, but it is already baked into all benchmarks and sizings since it is built into the embedded hypervisor, i.e. it is there even when you are running a single virtual machine on a system.

Utilization – Many experts have suggested that average utilization of VMware systems range in the 20% to 30% range. I found at least one analyst that said that the best run shops can drive their VMware systems up to 45%. I selected 45%, once again since I want to give all of the benefit of the doubt to Lintel systems. By comparison, many experts suggest that 85% utilization is reasonable for PowerVM based systems, but I selected 75% simply to not give any of the benefit of the doubt to Power that I was giving to x86.

SAPS – Since we are talking about SAP app servers, it is logical to use SAP benchmarks. The best result that I could find for a 2 socket Linux Intel Haswell-EP system was posted by Dell @ 90,120 SAPS (1). A similar 2-socket server from IBM was posted @ 115,870 SAPS (2).

IBM has internal sizing tables, as does every vendor, in which it estimates the SAPS capacity of different servers based on different OSs. One of those servers, the Power S822L, a 20-core Linux only system, is estimated to be able to attain roughly 35% less SAPS than the benchmark result for its slightly larger cousin running AIX, but this takes into consideration differences in MHz, number of cores and small differences due to the compilers used for SAP Linux binaries.

For our hypothetical comparison, let us assume that a customer needs approximately the SAPS capacity as can be attained with three Lintel systems running VMware including the 5% overhead mentioned above, a sustained utilization of 45% and 256GB per server. Extrapolating the IBM numbers, including no additional PowerVM overhead and a sustained utilization of 75%, results in a requirement of two S822L systems each with 386GB.

Lenovo, HP and Dell all offer easy to use configurators on the web. I ran through the same configuration for each: 2 @ Intel Xeon Processor E5-2699 v3 18C 2.3GHz 45MB Cache 2133MHz 145W, 16 @ 16GB x4 DIMMS, 1 @ Dual-port 10GB Base-T Ethernet adapter, 2 @ 300GB 10K RPM disk (2 @ 1TB 7200 RPM for Dell) and 24x7x4 hour 3-year warranty upgrades (3). Both the Lenovo and HP sites show an almost identical number for RedHat Enterprise Linux with unlimited guests (Dell’s was harder to decipher since they apply discounts to the prices shown), so for consistency, I used the same price for RHEL including 3-yr premium subscription and support. VMware also offers their list prices on the web and the same numbers were used for each system, i.e. Version 5.5, 2-socket, premium support, 3yr (4).

The configuration for the S822L was created using IBM’s eConfig tool: 2 @ 10-core 3.42 GHz POWER8 Processor Card, 12 @ 32GB x4 DIMMS, 1 @ Dual-port 10GB Base-T Ethernet adapter, 2 @ 300GB 10K RPM disk and a 24x7x4 hour 3-year warranty upgrade, RHEL with unlimited guests and 3yr premium subscription and support and PowerVM with unlimited guests, 3yr 24×7 support (SWMA). Quick disclaimer; I am not a configuration expert with IBM’s products much less those from other companies which means there may be small errors, so don’t hold me to these numbers as being exact. In fact, if anyone with more expertise would like to comment on this post and provide more accurate numbers, I would appreciate that. You will see, however, that all three x86 systems fell in the same basic range, so small errors are likely of limited consequence.

The best list price among the Lintel vendors came in at $24,783 including the warranty upgrade. RHEL 7 came in at $9,259 and VMware @ $9,356 with a grand total for of $43,398 and for 3 systems, $130,194. For the IBM Power System, the hardware list was $33,136 including the warranty upgrade, PowerVM for Linux $10,450 and RHEL 7 $6,895 for a grand total of $51,109 and for 2 systems, $102,218.

So, for equivalent effective SAPS capacity, Lintel systems cost around $130K vs. $102K for Power … and this is before we consider the reliability and security advantages not to mention scalability, peak workload handling characteristics, reduced footprint, power and cooling. Just to meet the list price of the Power System, the Lintel vendors would have to deliver a minimum of 22% discount including RHEL and VMware.

Conclusions:
For customers making HANA decisions, it is important to note that the app server does not go away and SAP fully support heterogeneous configurations, i.e. it does not matter if the app server is on a different platform or even a different OS than the HANA DB server. This means that Linux based Power Boxes are the perfect companion to HANA DB servers regardless of vendor.

For customers that are refreshing older Power app servers, the comparisons can be a little more complicated in that there is a reasonable case to be made for running app servers on enterprise class systems potentially also housing database servers in terms of higher effective utilization, higher reliability, the ability to run app servers in an IFL (Integrated Facility for Linux) at very attractive prices, increased efficiencies and improved speeds through use of virtual Ethernet for app to DB communications. That said, any analysis should start with like for like, e.g. two socket scale-out Linux servers, and then consider any additional value that can be gained through the use of AIX (with active memory expansion) and/or enterprise class servers with or without IFLs. As such, this post makes a clear point that, in a worst case scenario, scale-out Linux only Power Systems are less expensive than x86. In a best case scenario, the TCO, reliability and security advantages of enterprise class Power Systems make the value proposition of IBM Power even more compelling.

For customers that have already made the move to Lintel, the message is clear. You moved for sound economic, skills and standards based reasons. When it is time to refresh your app servers or add additional ones for growth or other purposes, those same reasons should drive you to make a decision to utilize IBM Power Systems for your app servers. Any customer that wishes to pursue such an option is welcome to contact me, your local IBM rep or an IBM business partner.

Footnotes:
1. Dell PowerEdge R730 – 2 Processors / 36 Cores / 72 Threads 16,500 users, Red Hat Enterprise Linux 7, SAP ASE 16, SAP enhancement package 5 for SAP ERP 6.0, Intel Xeon Processor E5-2699 v3, 2.3 Ghz, 262,144MB, Cert # 2014033, 9/10/2014

2. IBM Power System S824, 4 Processors / 24 Cores / 192 Threads, 21,212 Users, AIX 7.1, DB2 10.5, SAP enhancement package 5 for SAP ERP 6.0, POWER8, 3.52 Ghz, 524,288MB, Cert # 2014016, 4/28/2014

3. https://www-01.ibm.com/products/hardware/configurator/americas/bhui/flowAction.wss?_eventId=launchNIConfigSession&CONTROL_Model_BasePN=5462AC1&_flowExecutionKey=_cF5B38036-BD56-7C78-D1F7-C82B3E821957_k34676A10-590F-03C2-16B2-D9B5CE08DCC9
http://configure.us.dell.com/dellstore/config.aspx?c=us&cs=04&fb=1&l=en&model_id=poweredge-r730&oc=pe_r730_1356&s=bsd&vw=classic
http://h71016.www7.hp.com/MiddleFrame.asp?view=std&oi=E9CED&BEID=19701&SBLID=&AirTime=False&BaseId=45441&FamilyID=3852&ProductLineID=431

4. http://store.vmware.com/store/vmware/en_US/pd/productID.288070900&src=WWW_eBIZ_productpage_vSphere_Enterprise_Buy_US

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January 23, 2015 - Posted by | Uncategorized | , , , , , , , , , , , ,

4 Comments »

  1. How about SAPS/Thread? Since SAP is single threaded this is a rather important concept to make customers aware of

    Comment by full facts | January 27, 2015 | Reply

    • Each individual transaction may be single threaded, but since most SAP systems involve hundreds, thousands or more transactions and queries, the workload very quickly resembles a highly multi-threaded environment. So, yes, the performance of a single thread will depend on how many SAPS a given processor can deliver, but most SAP transactions, on the worst and slowest systems, still complete in sub-second times. To further complicate matters, Power utilizes intelligent threads, i.e. unlike some other multi-threaded processors. For example, if you have a set of workloads which will drive 16 total threads and you are running on an 8-core POWER8 system, only two threads per core will be utilized (unless you have used advanced tuning methods to force all of those threads onto just two cores). As a result, each core runs, in essence, in the equivalence of SMT2, not SMT8, meaning far more resources available per thread. If you measured or extrapolated the performance of those two threads, you would find much more SAPS/thread than if there were 64 total threads meaning that each core would actually be driving the full 8 threads each.

      Comment by Alfred Freudenberger | January 29, 2015 | Reply

  2. Found your blog based on IBM’s announcement of POWER8 support on HANA today. Do you have any benchmarks comparing IB/Haswell with Power8 on similar HANA workloads? Nice blog btw.

    Comment by WL Wong | May 4, 2015 | Reply

    • SAP provides a benchmark called BW-EML. All results that have been certified by SAP are posted on their web site: http://global.sap.com/solutions/benchmark/bweml-results.htm

      On that site, you will find IBM’s result @ 2B rows with a result of 192,750 Ad-hoc navigation steps/hr using an IBM Power Enterprise System 870, 4 processors / 40 cores / 320 threads, POWER8, 4.19 GHz, 32 KB (I) and 64 KB (D) L1 cache and 512 KB L2 cache per core, 8 MB L3 cache per core, 1024 GB main memory, certification # 2015024. You will also find the best Haswell result @ 2B rows published by Dell which achieved 172,450 Ad-hoc navigation steps/hr using a Dell PowerEdge R930, 4 processors / 72 cores / 144 threads, Intel Xeon Processor E7-8890 v3, 2.50 GHz, 64 KB L1 cache and 256 KB L2 cache per core, 45 MB L3 cache per processor, 1536 GB main memory, certification # 2015014.

      Put more simply, the IBM Power System delivered 12% better performance overall with 45% fewer cores resulting in slightly more than 2x performance per core. It is interesting to note that the Dell system required 50% more memory. Pure speculation on my part: the reason may have to due with memory throughput issues which can only be resolved by throwing in more DIMMS and memory controllers. By the way, there is absolutely no indication if Dell turned on memory Lockstep mode or not, but once again I will make a wild guess and suggest that they didn’t which means that any person that considers their result to be an indication of what might be possible in the real world is the same sort of person that thinks it is OK to drive a car without seat belts on their kids and with the airbags disabled.

      Comment by Alfred Freudenberger | June 29, 2015 | Reply


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