SAPonPower

An ongoing discussion about SAP infrastructure

SAP HANA support for HPE nPar on Superdome Flex update

In addition to the outstanding support for virtualization technologies like PowerVM for HANA and the lukewarm support for VMware by SAP, SAP also supports other technologies that allow larger systems to be subdivided into smaller nodes.  Note that I did not say virtualization, but subdivision.  Physical partitioning (PPAR) is a technology invented in the 1990s and only allows components, e.g. boards or NUMA nodes, to be allocated to a separate workload from others on the same physical system.

On October 22, 2018, SAP updated its SAP Note for HPE nPar technology.[i]  With this update, SAP now supports nPars with Superdome Flex.  Granularity is incredibly fine (not).  As noted in the SAP note, “Via nPartitions, the following  partition sizes are supported in terms of the number of sockets:

    • Skylake based architecture: ScaleUp 16s, 12s, 8s, 4s; ScaleOut 4s, 8s, 16s

Or to put it in terms of cores, each socket has 28 cores, so granularity is 112 cores.  You need only 20 cores?  No problem, you get to consume 112.  You need 113 cores? Also no problem, you get to consume 224 cores.  But, on the positive side, these npars are “electrically isolated” which has 2 really important implications.  First, the only way to isolate one or more Superdome Flex drawers into a separate nPar is to physically change the mesh wiring of the entire system.  That means that if you decide to change the configuration of nPars, dynamic changes would be the exact opposite of what is supported.  In fact, according to customer reports, HPE requires a Statement of Work service contract to come out and rewire the system and it takes multiple days … one customer reported multiple weeks.  The second implication is that all resources on the node(s) in an nPar are dedicated to that nPar.  In the above example, if you need 20 cores, you probably require around a ½ TB of memory for BW or 1TB of memory for S/4.  It is possible to configure an nPar with as little as 1.5TB of memory which means that you might waste an entire TB if you only need ½ TB.  Alternately, if you have other workloads on other nPars that require more cores and memory and you want to keep all drawers consistent to allow for future changes, you might actually have up to 6TB per drawer meaning much more wasted memory if you only require ½ TB for a particular workload.  By the way, the only other elements that are shared when a system is broken up into physically isolated nPars are the frame(s), power supplies and the RMC – Rack Management Controller.  PCIe cards cannot be shared due to the physical isolation, so by using nPars, you essentially take a very expensive system and carve it into a bunch of smaller and very expensive, isolated systems which are difficult to reconfigure.  Alternately, if you really must use HPE technology for smaller workloads, you could purchase smaller systems at much lower prices.

I have really been trying to scratch my head and understand why anyone would want this type of 1990s era partitioning technology.  HPE certainly does because it results in higher profits from selling larger systems with more aggregate capacity while giving the false appearance of flexibility.  For customers, on the other hand, it offers massive waste and very limited flexibility.

My advice: Don’t be a sucker and get taken in by HPE’s misdirection play.  Either purchase appropriately sized systems for each workload or purchase systems that offer real virtualization, such as IBM Power Systems, with fine grained allocation of resources sharing of components such as PCIe adapters and true server consolidation, but don’t purchase one of these massive HPE systems and then eliminate any perceived value of using such a large system by cutting it up into smaller systems.

 

 

[i]2103848 – SAP HANA on HPE nPartitions in production

 

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March 25, 2019 Posted by | Uncategorized | , , , , , , , , , , , | Leave a comment

HPE Superdome is dead, but HPE marketing continues its deceptive ways.

Today, 11/6/17, HPE announced the “New” Superdome Flex.  If you did not look too closely, you would think that this was some sort of descendant of Superdome.  After all, the Integrity Superdome took the original Superdome and replaced PA-RISC chips and the SX1000 cell controller with Itanium chips and a faster SX2000 cell controller.  Superdome 2 took this further by upgrading to the latest Itanium chips, an even faster SX3000 cell controller and moved from a cell board to a blade configuration.  Superdome X changed out the Itanium chips for Intel Xeon chips which it upgraded over several generations.  So, it would be only natural to think that Superdome Flex did something similar and that is exactly what HPE wants you to think.

Except, this is not even remotely like any prior Superdome and has inherited almost nothing from it.  In fact, this is a very straightforward descendant of the SGI UV 300H, which HPE renamed the MC990 X after the acquisition.  A glance at the front of the “new” system shows the same basic design, a 4-socket, 5U chassis even down to the unique diagonal handles on the fans, but they apparently moved the NUMAlink fabric ports (no longer called that; renamed Superdome Flex ports) from the back to the front, perhaps to get rid of a little of the rats nest of cables which defined the SGI UV 300H.  This means there is no SX3000 or cross bar switch in the Flex and the blade design is gone.  Even the memory DIMMS are different which implies that nothing could be moved from an old Superdome X to a new “Flex” other than perhaps some old PCIe adapters.

So, if the entire design is based on an SGI acquired technology and it shares nothing from its “namesake”, one would need to avoided that course in ethics in high school or college to find it appropriate to suggest to customers that this is a related technology.  Imagine if Honda changed the engine, frame, transmission, trim and body style but called their new car an Accord “Flex” because it used the same bumper and tire sizes, would you feel as if they were trying to manipulate you?

Back to the more important topic, Superdome is now dead!  I have been saying this for a while and blogged about this several months ago.  I suggested that any customer considering investing in this technology view it as instantly obsolete and a sunk investment.  I pointed out the huge investment in ccNUMA interconnect technologies and how it was hard to imagine how HPE could afford to invest in 2 different ones at the same time, so only one system was likely to survive.  I explained that the SGI technology offered more space and power to host the new, larger, higher wattage and heat dissipating Skylake processors.  It appears that my projections were correct.  For customers that ignored that advice, I just hope you got a really great price and don’t mind paying a lot for old technology for any upgrades or dumping your old systems at a huge financial loss.  For any customer still considering a Superdome X, the writing is no longer on the wall.  It is on HPE’s web site.  https://news.hpe.com/hewlett-packard-enterprise-unveils-the-worlds-most-scalable-and-modular-in-memory-computing-platform/

Currently, no white papers have been published showing the architecture and detailed specs of this “new” system, only a relatively high level “Spec” sheet.  Perhaps HPE is too embarrassed to publish this since it would likely resemble the SGI UV 300H in way too many ways, including the old rats nest of 4-bit wide interconnect cables.  Once they do, I will investigate and will likely publish a separate post to share what I find.

On the SAP front, new HANA appliance specs have been published for “Flex”.   It is interesting, and again embarrassing for HPE, that only up to 8-socket configs are shown, with less BWoH memory support @ 6TB max than the old, and now obsolete, Superdome X.  Even more interesting is the lack of SoH and S/4 configs, and I have a suspicion as to why.  Turns out that the spec sheet does have one interesting point after all.  It shows the maximum size memory DIMMS are 64GB and the number of DIMMS slots is 48 with a max supported memory of 3TB per chassis, i.e. half of what is necessary to support the 6TB per 4-sockets that other competing Intel vendors support.

So, if you need a supported HANA configuration today with current generation processors for BWoH beyond 6TB, look at any vendor other than HPE with 8-socket Skylake systems or IBM Power Systems.  If you need a supported SoH or S/4 configuration with current gen processors, look at any vendor other than HPE and beyond 12TB, only IBM Power Systems is supported at this level.

November 6, 2017 Posted by | Uncategorized | , , , , , , , , , , | Leave a comment