SAP performance report sponsored by HP, Intel and VMware shows startling results
Not often does a sponsored study show the opposite of what was intended, but this study does. An astute blog reader alerted me about a white paper sponsored by HP, VMware and Intel by an organization called Enterprise Strategy Group (ESG). The white paper is entitled “Lab Validation Report – HP ProLiant DL980, Intel Xeon, and VMware vSphere 5 SAP Performance Analysis – Effectively Virtualizing Tier-1 Application Workloads – By Tony Palmer, Brian Garrett, and Ajen Johan – July 2011.” The words that they used to describe the results are, as expected, highly complementary to HP, Intel and VMware. In this paper, ESG points out that almost 60% of the respondents to their study have not virtualized “tier 1” applications like SAP yet but expect a rapid increase in the use of virtualization. We can only assume that they only surveyed x86 customers as 100% of Power Systems customers are virtualized since the PowerVM hypervisor is baked into the hardware and firmware of every system and can’t be removed. Nevertheless, it is encouraging that customers are moving in the right direction and that there is so much potential for the increased use of virtualization.
ESG provided some amazing statistics regarding scalability. ESG probably does not realize just how bad this makes VMware and HP look, otherwise, they probably would not have published it. They ran an SAP ECC 6.0 workload which they describe as “real world” but for which they provide no backup as to what this workload was comprised of, so it is possible that a given customer’s workload may be even more intensive than the one tested. They ran a single VM with 4 vcpu, then 8, 16 and 32. They show both the number of users supported as well as the IOPS and dialog response time. Then, in their conclusions, they state that scaling was nearly linear. This data shows that when scaling from 4 to 32 cores, an 8x increase, the number of users supported increased from 600 to 3,000, a 5x increase. Put a different way, 5/8 = .625 or 62.5% scalability. Not only is this not even remotely close to linear scaling, but it is an amazing poor level of scalability. IOPS, likewise, increased from 140 to 630 demonstrating 56.3% scalability and response time went from .2 seconds to 1 second, which while respectable, was 5 times that of the 4 vcpu VM.
ESG also ran a non-virtualized test with 32 physical cores. In this test, they achieved only 4,400 users/943 IOPS. Remember, VMware is limited to 32 vcpu which works out to the equivalent of 16 cores. So, with twice the number of effective physical cores, they were only able to support 46.7% more users and 49.7% more IOPS. To make matters much worse, response time almost doubled to 1.9 seconds.
ESG went on to make the following statement: “Considering that the SAP workload tested utilized only half of the CPU and one quarter of the available RAM installed in the DL980 tested, it is not unreasonable to expect that a single DL980 could easily support a second virtualized SAP workload at a similarly high utilization level and/or multiple less intensive workloads driven by other applications.” If response time is already borderline poor with VMware managing only a single workload, is it reasonable to assume that response time will go up or down if you add a second workload? If IOPS are not even keeping pace with the poor scalability of vcpu, it is reasonable to assume that IOPS will all of a sudden start improving faster? If you have not tested the effect of running a second workload, is it reasonable to speculate what might happen under drastically different conditions? This is like saying that on a hot summer day, an air conditioner was able to maintain a cool temperature in a sunny room with half of the chairs occupied and therefore it is not “unreasonable” to assume that it could do the same with all chair occupied. That might be the case, but there is absolutely no supporting evidence to support such a speculation.
ESG further speculates that because this test utilized default values for BIOS, OS, SAP and SQL Server, performance would likely be higher with tuning. … And my car will probably go faster if I wash it and add air to the tires, but by how much?? In summary and I am paraphrasing, ESG says that VMware, Intel processors and HP servers are ready for SAP primetime providing reliability and performance while simplifying operations and lowering costs. Interesting that they talk about reliability yet they, once again, provide no supporting evidence and did not mention a single thing about reliability earlier in the paper other than to say that the HP DL980 G7 delivers “enhanced reliability”. I certainly believe every marketing claim that a company makes without data to back it up, don’t you?
There are three ways that you can read this white paper.
- ESG has done a thorough job of evaluating HP x86 systems, Intel and VMware and has proven that this environment can handle SAP workloads with ease
- ESG has proven that VMware has either incredibly poor scalability or high overhead or both
- ESG has limited credibility as they make predictions for which they have no data to support their conclusions
While I might question how ESG makes predictions, I don’t believe that they do a poor job at performance testing. They seem to operate like an economist, i.e. they are very good at collecting data but make predictions based on past experience, not hard data. When is the last time that economists correctly predicted market fluctuations? If they did, they would all be incredibly rich!
I think it would be irresponsible to say that VMware based environments are incapable of handling SAP workloads. On the contrary, VMware is quite capable, but there are significant caveats. VMware does best with small workloads, e.g. 4 to 8 vcpu, not with larger workloads e.g. 16 to 32 vcpu. This means if a customer utilizes SAP on VMware, they will need more and smaller images than they would on excellent scaling platforms like IBM Power Systems, which drives up management costs substantially and reduces flexibility. By way of comparison, published SAP SD 2-tier benchmark results for IBM Power Systems utilizing POWER7 technology show 99% scalability when comparing the performance of a 16-core to a 32-core system at the same MHz, 89.3% scalability when comparing a 64-core to a 128-core system with a 5% higher MHz, which when normalized to the same MHz shows 99% scalability even at this extremely high performance level.
The second caveat for VMware and HP/Intel systems is in that area that ESG brushed over as if it was a foregone conclusion, i.e. reliability. Solitaire Interglobal examined data from over 40,000 customers and found that x86 systems suffer from 3 times or more system outages when comparing Linux based x86 systems to Power Systems and up to 10 times more system outages when comparing Windows based x86 systems to Power Systems. They also found radically higher outage durations for both Linux and Windows compared to Power and much lower overall availability when looking at both planned and unplanned outages in general: http://ibm.co/strategicOS and specifically in virtualized environments: http://ibm.co/virtualizationplatformmatters. Furthermore, as noted in my post from late last year, http://saponpower.wordpress.com/2011/08/29/vsphere-5-0-compared-to-powervm/, VMware introduces a number of single points of failure when mission critical applications demand just the opposite, i.e. the elimination of single points of failure.
I am actually very happy to see this ESG white paper, as it is has proven how poor VMware scales for large workloads like SAP in ways that few other published studies have ever exposed. Power Systems continues to set the bar very high when it comes to delivering effective virtualization for large and small SAP environments while offering outstanding, mission critical reliability. As noted in http://saponpower.wordpress.com/2011/08/15/ibm-power-systems-compared-to-x86-for-sap-landscapes/, IBM does this while maintaining a similar or lower TCO when all production, HA and non-production systems, 3 years of 24x7x365 hardware maintenance, licenses and 24x7x365 support for Enterprise Linux and vSphere 5.0 Enterprise Plus … and that analysis was done back when I did not have ESG’s lab report showing how poorly VMware scales. I may have to revise my TCO estimates based on this new data.