Are You Ready For z Systems Workload Pricing for Cloud (zWPC) for z/OS?

Recently IBM announced the z Systems Workload Pricing for Cloud (zWPC) for z/OS pricing mechanism, which can minimize the impact of new Public Cloud workload transactions on Sub-Capacity license charges.  Such benefits will be delivered where higher Public Cloud workload transaction volumes may cause a spike in machine utilization.  Of course, if this looks familiar and you have that feeling of déjà vu, this is a very similar mechanism to Mobile Workload Pricing (MWP)…

Put simply, zWPC applies to any organization that has implemented Sub-Capacity pricing via the basic AWLC or AEWLC pricing mechanisms, for the usual MLC software suspects, namely z/OS, CICS, DB2, IMS, MQ and WebSphere Application Server (WAS).  An eligible transaction is one classified as Public Cloud originated, connecting to a z/OS hosted transactional service and/or data source via a REST or SOAP web service.  Public Cloud workloads are defined as transactions processed by named Public Cloud applications transactions identified as originating from a recognized Public Cloud offering, including but not limited to, Amazon Web Services (AWS), Microsoft Azure, IBM Bluemix, et al.

As per MWP, SCRT calculates the R4HA for Public Cloud transaction GP MSU resource usage, subtracting 60% of those values from the traditional Sub-Capacity software eligible MSU metric, with LPAR granularity, for each and every reporting hour.  The software program values for the same hour are aggregated for all Sub-Capacity eligible LPARs, deriving an adjusted Sub-Capacity value for each reporting hour.  Therefore SCRT determines the billable MSU peak for a given MLC software program on a CPC using the adjusted MSU values.  As per MWP, this will only be of benefit, if the Public Cloud originated transactions generate a spike in the current R4HA.

One of the major challenges for implementing MWP was identifying those transactions eligible for consideration.  Very quickly IBM identified this challenge and offered a WorkLoad Manager (WLM) based solution, to simplify reporting for all concerned.  This WLM SPE (OA47042), introduced a new transaction level attribute in WLM classification, allowing for identification of mobile transactions and associated processor consumption.  These Reporting Attributes were classified as NONE, MOBILE, CATEGORYA and CATEGORYB.  Obviously IBM made allowances for future workload classifications, hence it would seem Public Cloud will supplement Mobile transactions.

In a previous z/OS Workload Manager (WLM): Balancing Cost & Performance blog post, we considered the merits of WLM for optimizing z/OS software costs, while maintaining optimal performance.  One must draw one’s own conclusions, but there seemed to be a strong case for WLM reporting to be included in the z/OS MLC Cost Manager toolkit.  The introduction of zWPC, being analogous to MWP, where reporting can be simplified with supplied and supported WLM function, indicates that intelligent and proactive WLM reporting makes sense.  Certainly for 3rd party Soft-Capping solutions, the ability to identify MWP and zWPC eligible transactions in real-time, proactively implementing MSU optimization activities seems mandatory.

The Workload X-Ray (WLXR) solution from zIT Consulting delivers this WLM reporting function, seamlessly integrating with their zDynaCap and zPrice Manager MSU optimization solutions.  Of course, there is always the possibility to create your own bespoke reports to extract the relevant information from SMF records and subsystem diagnostic data, for input to the SCRT process.  However, such a home-grown process will only work on a monthly reporting basis and not integrate with any Soft-Capping MSU management, which will ultimately control z/OS MLC costs.

In conclusion, from a big picture viewpoint, in the last 2 years or so, IBM have introduced several new Sub-Capacity pricing mechanisms to help System z Mainframe users optimize z/OS MLC costs, namely Mobile Workload Pricing (MWP), Country Multiplex Pricing (CMP) and now z Systems Workload Pricing for Cloud (zWPC).  In theory, at least one of these new pricing mechanisms should deliver benefit to the committed System z user, deploying this server for strategic and Mission Critical workloads.  With the undoubted strategic importance associated with Analytics, Blockchain, Cloud, DevOps, Mobile, Social, et al, the landscape for System z workloads is rapidly evolving and potentially impacting those sacrosanct legacy Mission Critical workloads.  Seemingly the realm of possibility exists that Cloud and Mobile originated transactions will dominate access to System z Mainframe System Of Record (SOR) data repositories, which generates a requirement to optimize associated MLC costs accordingly.  Of course, for some System z users, such Cloud and Mobile access might not be on today’s to-do list, but inevitably it’s on the horizon, and so why not implement the instrumentation ability ASAP!

z/OS Workload Manager (WLM): Balancing Cost & Performance

A sophisticated mechanism is required to orchestrate the allocation of System z resources (E.g. CPU, Memory, I/O) to multiple z/OS workloads, requiring differing business processing priorities. Put very simply, a mechanism is required to translate business processing requirements (I.E. SLA) into an automated and equitable z/OS performance manager. Such a mechanism will safeguard the highest possible throughput, while delivering the best possible system responsiveness. Ideally, such a mechanism will assist in delivering this optimal performance, for the lowest cost; for z/OS, primarily Workload License Charges (WLC) related. Of course, the Workload Management (WLM) z/OS Operating System component delivers this functionality.

A rhetorical question for all z/OS Performance Managers and z/OS MLC Cost Managers would be “how much importance does your organization place on WLM and how proactively do you manage this seemingly pivotal z/OS component”? In essence, this seems like a ridiculous question, yet there is evidence that suggests many organizations, both customer and ISV alike, don’t necessarily consider WLM to be a fundamental or high priority performance management discipline. Let’s consider several reasons why WLM is a fundamental component in balancing cost and performance for each and every z/OS environment:

  • CPU (MSU) Resource Capping: Whatever the capping method (I.E. Absolute, Hard, Soft), WLM is a controlling mechanism, typically in conjunction with PR/SM, determining when capping is initiated, how it is managed and when it is terminated. Therefore from a dispassionate viewpoint, any 3rd party ISV product that performs MSU optimization via soft capping mechanisms should ideally consider the same CPU (E.g. SMF Type 70, 72, 99) instrumentation data as WLM. Some solutions don’t offer this granularity (E.g. AutoSoftCapping, iCap).
  • MLC R4HA Cost Management: WLM is the fundamental mechanism for controlling this #1 System z software TCO component; namely WLM collects 48 consecutive metric CPU MSU resource usage every 5 Minutes, commonly known as the Rolling 4 Hour Average (R4HA). In an ideal world, an optimally managed workload that generates a “valid monthly peak”, will fully utilize this “already paid for” available CPU MSU resource for the remainder of the MLC eligible month (I.E. Start of the 2nd day in a calendar month, to the end of the 1st day in the next calendar month). More recently, Country Multiplex Pricing (CMP) allows an organization to move workloads between System z server (I.E. CPC) structures, without cost consideration for cumulative R4HA peaks. Similarly, Mobile Workload Pricing (MWP) reporting will be simplified with WLM service definitions in z/OS 2.2. Therefore it seems prudent that real-time WLM management, both in terms of real-time reporting and pro-active decision making makes sense.
  • System z Server CPU Management: As System z server CPU chips evolve (E.g. CPU Chip Cache Hierarchy and Relative Nest Intensity), there are complementary changes to the z/OS Operating System management components. For example, HiperDispatch Mode delivers CPU resource usage benefit, considering CPU chip cache resources, intelligently allocating workload to as few logical processors as possible. It therefore follows that prioritization of workloads via WLM policy definitions becomes increasingly important. In this instance one might consider that CPU MF (SMF Type 113) and WLM Topology (SMF Type 99) are complementary reporting techniques for System z server design and management.

Since its announcement in September 1994 (I.E. MVS/ESA Version 5), WLM has evolved to become a fully-rounded and highly capable z/OS System Resources Manager (SRM), simply translating business prioritization policies into dynamic function, optimizing System z CPU, Memory and I/O resources. More recently, WLM continues to simplify the management of CPU chip cache hierarchy resources, while reporting abilities gain in strength, with topology reporting and the promise of simplified MWP reporting. Moreover, WLM resource management becomes more granular and seemingly the realm of possibility exists to “micro manage” System z performance, as and if required. Conversely, WLM provides the opportunity to simplify System z performance management, with intelligent workload differentiation (I.E. Subsystem Enclave, Batch, JES, USS, et al).

Quite simply, IBM are providing the instrumentation and tools for the 21st Century System z Performance and Software Cost Subject Matter Expert (SME) to deliver optimal performance for minimal cost. However, it is incumbent for each and every System z user to optimize software TCO, proactively implementing new processes and leveraging from System z functions accordingly.

Returning to that earlier rhetorical question about the importance of WLM; seemingly its importance is without doubt, primarily because of its instrumentation and management abilities of increasingly cache rich System z CPU chips and its fundamental role in controlling CPU MSU resource, vis-à-vis the R4HA.

Although IBM will provide the System z user with function to optimize system performance and cost, for obvious commercial reasons IBM will not reduce the base cost of System z MLC software. However, recent MLC pricing announcements, namely Country Multiplex Pricing (CMP), Mobile Workload Pricing (MWP) and Collocated Application Pricing (zCAP) provide tangible options to reduce System z MLC TCO. Therefore the System z user might need to consider how they can access real-time WLM performance metrics, intelligently combining this instrumentation data with function to intelligently optimize CPU MSU resource, managing the R4HA accordingly.

Workload X-Ray (WLXR) from zIT Consulting simplifies WLM performance reporting, enabling users to drill down into the root cause of performance variances in a very fast and easy way. WLXR assists in root cause problem determination by zooming in, starting from a high level overview, going right down to detailed Service Class performance information, such as the Performance Index (PI), showing potential bottleneck situations during peak time. Any system overhead considerations are limited, as WLXR delivers meaningful real time information on a “need to know” basis.

A fundamental design objective for WLXR is data reduction, only delivering the important information required for timely and professional workload management. Straight to the point information instead of data overload, sometimes from a plethora of data sources (E.g. SMF, System Monitors, et al). WLXR incorporates the following easy-to-use functions:

  • Simplified Data Collection & Storage: Minimal system overhead TCP/IP based agents periodically (E.g. 5, 15, 60 Minutes) collect CPU (Type 70) and WLM (Type 72) data. Performance data is stored centrally in near real-time, building a historical repository with intelligent analytics for meaningful information presentation.
  • Intelligent GUI Based Information Presentation: Meaningful decision based reports and graphs detailing CPU (E.g. MSU, R4HA, Weight) and WLM (E.g. Service Class, Performance Index, Response Time, Transaction Workflow) resource usage. A drill-down design provides a granularity of data presentation, for Management Summary to 3rd Level Technical Diagnostics use.
  • Corporate Identity Branding: A modular template design, allowing for easy corporate identity branding, with flexibility to easily add additional reports, as and if required.

Without doubt, WLM is a significant z/OS System Resources Management function, simplifying the translation of business workload requirements (I.E. Service Level Agreement) into timely and proactive allocation of major System z hardware resources (I.E. CPU, Memory, I/O). This management of System z resources has been forever thus for 20+ years, while WLM has always offered “software cost control” functionality, working with the various and evolving CPU capping techniques. What might not be so obvious, is that there is a WLM orientated price versus performance correlation, which has become more evident in the last 5 years or so. Whether Absolute Capping, HiperDispatch, Mobile Workload Pricing, Country Multiplex Pricing or evolving Soft Capping techniques, the need for System z users to integrate z/OS MLC pricing considerations alongside WLM performance based management is evident.

Historically there was not a clear and identified need for a z/OS Performance/Capacity Manager to consider MLC costs in their System z server designs. However, there is a clear and present danger that this historic modus operandi continues and there will only be one financial winner, namely IBM, with unnecessarily high MLC charges. Each and every System z user, whether large or small, can safeguard the longevity of their IBM Mainframe platform by recognizing and deploying proactive and current System z MLC cost management processes.

All too often it seems that capping can be envisaged as punitive, degrading system performance to reduce System z MLC costs. Such a notion needs to be consigned to history, with a focussed perspective on MSU optimization, where the valuable and granular MSU resource is allocated to the workload that requires such CPU resource, with near real-time performance profiling. If we perceive MSU optimization to be R4HA based and that IBM are increasing WLM function to assist this objective, CPU capping can be a benefit that does not adversely impact performance. As previously stated, once a valid R4HA peak has occurred, that high MSU watermark is available for the remainder of the MLC billing period. Similarly at a more granular level, once a workload has peaked and its MSU usage declines, the available MSU can be redirected to other workloads. With the introduction of Country Multiplex Pricing, System z users no longer need to concern themselves about creating a higher R4HA peak, when moving workloads between System z servers.

Quite simply, from the two most important perspectives, performance and cost optimization, WLM provides the majority of functionality to assist System z users get the best performance for the lowest cost. Analytics based products like Workload X-Ray (WLXR) assist this endeavour, analysing WLM data in near real-time from a performance and MLC cost perspective. It therefore follows that if this important information is also available for sophisticated MSU optimization solutions, which consider WLM performance (E.g. zDynaCap, zPrice Manager), then proactive performance and cost management follows. It’s hard to envisage how a fully-rounded MSU optimization decision can be implemented in near real-time, from an MSU optimization solution that does not consider WLM performance metrics…

z13 WLC Software Pricing Updates: Are You Ready?

Along with the z13 hardware announcement were several very obvious WLC pricing announcements, but more importantly, two hidden Statements Of Direction (SOD) or pre-announcements.

I guess we can all remember the “zSeries Technology Dividend” where put simply, when upgrading zSeries servers, users would benefit from a ~10%+ software price versus performance benefit.  Does anybody still remember the IBM Mainframe Charter from 2003?  That was the document that first referenced this price/performance benefit, which became known as the “technology dividend”.  Specifically, this document stated:

IBM lowered MSU values incorporated in the z990 microcode by approximately 10 percent, resulting in IBM software savings for IBM zSeries software products with MSU-based pricing.  These reduced MSUs do not indicate a change in machine performance. Superior performance and technology within the z990 has allowed IBM to provide improved software prices for key IBM zSeries operating system and middleware software products.

Put really simply, for z990, z9 and z10 server upgrades, IBM delivered this ~10% benefit with faster CPU chips.  Therefore, no noticeable impact on Software Pricing, Capacity Planning or Performance Measurement processes.  However, with the z196/z114, this ~10% benefit could no longer be delivered by CPU chip hardware speed enhancements.  To compensate, IBM introduced the Advanced Workload License Charges (AWLC) pricing regime.  AWLC is an evolution of the Variable (VWLC) pricing regime, lowering per MSU costs for WLC eligible products (E.g. z/OS, CICS, DB2, IMS, WebSphere/MQ, et al).  Hence delivering the ~10% price/performance benefit when upgrading from a z10 to a z196 or z114 (AEWLC) server.

Of course, when upgrading to the zEC12 or zBC12, further refinement of AWLC pricing was required, to deliver this the ~10% price/performance benefit.  Hence, IBM introduced the AWLC Technology Transition Offerings (TTO), lowering AWLC prices for zXC12 and now z13 zSeries servers.

For z13, IBM announced the following z13 AWLC Technology Transition Offerings:

  • Technology Update Pricing for the IBM z13 (TU3): When stand-alone z13 servers are priced with AWLC, or when all the servers in an aggregated Sysplex or Complex are z13 servers priced with AWLC, these servers receive a reduction to AWLC pricing which is called.  Quantity of z13 Full Capacity MSUs for a stand-alone server, or the sum of Full Capacity MSUs in an actively coupled Parallel Sysplex or Loosely Coupled Complex made up entirely of z13 servers.  AWLC discounts range from 4% (4-45 MSU) to 14% (5477+ MSU).
  • AWLC Sysplex Transition Charges (TC2): When two or more machines exist in an aggregated Sysplex or Complex & at z13, zEC12, or zBC12 server & at least one is a z196 or z114 server, with no older technology machines included, they will receive a reduction to AWLC pricing across the aggregated Sysplex or Complex. This reduction provides a portion of the benefit related to the Technology Update Pricing for AWLC (TU1) based upon the proportion of zEC12 or zBC12 server capacity in the Sysplex or Complex.  AWLC discounts range from 0.5% (0-20% z13/zXC12 MSU) to 4.5% (81%-<100% z13/zXC12 MSU).
  • AWLC Sysplex Transition Charges (TC3): When two or more machines exist in an aggregated Sysplex or Complex & at least one is a z13 server & at least one is a zEC12 or zBC12 server, with no older technology machines included, they will receive a reduction to AWLC pricing across the aggregated Sysplex or Complex. This reduction provides a portion of the benefit related to the IBM z13 TU3 offering, based on the total Full Capacity MSU of all z13, zEC12, & zBC12 Machines in the Sysplex or Complex.  AWLC discounts range from 2.8% (4-45 MSU) to 9.8% (5477+ MSU).

These AWLC software pricing announcements are Business As Usual (BAU) and to be expected, but if we dig slightly deeper into the z13 announcements, we will find two other pre-announcements of interest!

Since introducing sub-capacity and WLC pricing regimes, IBM have continually evolved zSeries software sub-capacity pricing mechanisms, with zNALC, AWLC, IWP and more recently MWP offerings.  From a generic viewpoint, with the exception of zNALC, a niche new workload price offering, these pricing announcements did not challenge the “status quo”, where aggregated MSU and large LPAR structures were the ideal.  So why might the upcoming z13 (E.g. Q2 2015) pricing announcements be of note?  Primarily because they challenge the notion of having separate structural entities (I.E. Sysplex Coupled zSeries Servers & LPARS) for existing and new workloads.

Country Multiplex Pricing (CMP): A major evolution, essentially eliminating prior Sysplex pricing rules, requiring that systems be interconnected and/or sharing the same data in order to be eligible for aggregation of MLC software pricing charges.  A Multiplex is defined as the collection of all z Systems within a country.  Therefore, sub-capacity usage will be measured & reported as a single machine, regardless of the connectivity or data sharing configurations.  A new sub-capacity reporting tool is being implemented & clients should expect a transition period as the new pricing model is implemented.  This should allow flexibility to move & run work anywhere, eradicating multiple workload peaks when workloads move between machines.  Ultimately the cost of growth is reduced with one price per product based on MLC capacity growth anywhere in the country.CMP should facilitate for flexible deployment and movement of business workloads between all zSeries Servers located within a country, without impacting MLC billing.  For the avoidance of doubt, this will assist the customer in safeguarding they don’t encounter duplicate MLC peaks as a result of moving an LPAR workload from one zSeries Server to another.  It also removes all Sysplex aggregation considerations, Single Version Charging (SVC) time limits and Cross Systems Waivers (CSW).  Most notably, the cost per MSU for additional capacity will be optimized, being based upon total Multiplex MSU capacity.

IBM Collocated Application Pricing (ICAP): Previously, new applications (zNALC) required a separate LPAR to avoid increases in other MLC software charges.  ICAP facilitates new eligible applications be charged as if they are running in a dedicated environment.  Technically they are integrated with other (non-eligible) workloads.  Software supporting the new application will not impact the charges for other MLC software collocated in the same LPAR.  ICAP appears as an evolution of the Mobile Workload Pricing (MWP) for z/OS pricing mechanism.  ICAP will use an enhanced MWRT, implemented as a z/OS application.  ICAP applies to z13, zXC12, z196/z114 servers.  IBM anticipates that ICAP will deliver zNALC type price benefit, discounting ~50% of ICAP eligible software MSU.

Seemingly IBM have learned from the lessons of IWP, where at first glance, software discounts were attractive, but not at the cost of a separate LPAR.  From a reporting viewpoint, there are similarities to Mobile Workload Pricing for z/OS (MWP), but most notably, pricing is largely zNALC based.  Therefore collocating new workloads in the same LPAR as existing workloads, but with the best price performance of any pricing regime, except zNALC, which is a niche and special edition software pricing metric.

In conclusion, CMP and ICAP are notable WLC pricing regime updates, because they do challenge the status quo of MSU aggregation via Sysplex coupled servers and the ability to collocate new and existing workloads in the same LPAR.  On the one hand, simplified pricing considerations from a granular per MSU cost viewpoint.  However, to optimize price versus performance, arguably the savvy Data Centre will now require a higher level of workload management, safeguarding optimum MSU capacity usage and associated performance.

zPrice Manager is an evolution of the typical soft-capping approach, which can be IBM function based, namely Defined Capacity (DC) or Group Capacity Limit (GCL), or ISV product based.  ISV products typically allow MSU management with dynamic MSU capacity resource management between LPAR, LPAR Group & CPC structures, ideally with Workload Manager (WLM) interaction.  If plug & play simple MSU management is required, these traditional IBM or 3rd party ISV approaches will still work with CMP and ICAP, but will they maximize WLC TCO?

The simple answer is no, because CMP allows the movement of workloads between zSeries Servers.  Therefore if WLC product (I.E. z/OS, CICS, DB2, IMS, WebSphere/MQ) pricing is to be country wide, and optimum WLM performance is to be maintained, a low level granularity of MSU management is required.

zPrice Manager from zIT Consulting allows this level of WLC software product management, with a High Level REXX programmatic interface, and the ability to store real life MSU profile data as callable REXX variables.  Similar benefits apply to ICAP workloads, where different WLM policies might be required for the same WLC product, deployed on the same collocated workload LPAR.  Therefore the savvy data centre will safeguard they optimize MSU TCO via MWP and/or ICAP pricing regimes, without impacting business application performance.

In conclusion, the typical z13 AWLC software pricing updates are Business As Usual (BAU) and can be implemented, as and when required and without consideration.  Conversely, CMP and ICAP can deliver significant future benefit and should be considered in zSeries Server capacity planning forecasts.

Bottom Line Recommendation: Each and every zSeries Server user, whether large or small, should initiate contact with their IBM account teams, for CMP and ICAP briefings, allowing them to consider how they might benefit from these new WLC software pricing regimes.

IBM Mainframe: Workload License Charges (WLC) Pros & Cons

It is estimated that less than half of eligible IBM Mainframe customers deploy the VWLC pricing mechanism, which in theory, is the lowest cost IBM software pricing metric.  Why?  In the first instance, let’s review the terminology…

Workload License Charges (WLC) is a monthly software license pricing metric applicable to IBM System z servers running z/OS or z/TPF in z/Architecture (64-bit) mode.  The fundamental ethos of WLC is a “pay for what you use” mechanism, allowing a lower cost of incremental growth and the potential to manage software cost by managing associated workload utilization.

WLC charges are either VWLC (Variable) or FWLC (Flat).  Not all IBM Mainframe software products are classified as VWLC eligible, but the major software is, including z/OS, CICS, DB2, IMS and WebSphere MQ, where these products are the most expensive, per MSU.  What IBM consider to be legacy products, are classified as FWLC.  More recently a modification to the VWLC mechanism was announced, namely AWLC (Advanced), strictly aligned with the latest generation of zSeries servers, namely zEC12, z196 and z114.  For the smaller user, the EWLC (Entry) mechanism applies, where AEWLC would apply for the z114 server.  There is a granular cost structure based on MSU (CPU) capacity that applies to VWLC and associated pricing mechanisms:

Band MSU Range
Base 0-3 MSU
Level 0 4-45 MSU
Level 1 46-175 MSU
Level 2 176-315 MSU
Level 3 316-575 MSU
Level 4 576-875 MSU
Level 5 876-1315 MSU
Level 6 1316-1975 MSU
Level 7 1976+ MSU

Put simply, as the MSU band increases, the related cost per MSU decreases.

IBM Mainframe users can further implement cost control by specifying how much MSU resource they use by deploying Sub-Capacity and Soft Capping techniques.  Defined Capacity (DC) allows the sizing of an LPAR in MSU, and so said LPAR will not exceed this MSU amount.  Group Capacity Limit (GCL) extends the Defined Capacity principle for a single LPAR to a group of LPARs, and so allowing MSU resource to be shared accordingly.  A potential downside of GCL is that is one LPAR of the group can consume all available MSU due to a rogue transaction (E.g. loop).

Sub-Capacity software charges are based upon LPAR hardware utilization, where the product runs, measured in hourly intervals.  To smooth out isolated usage peaks, a Rolling 4-Hour Average (R4HA) is calculated for each LPAR combination, and so software charges are based on the Monthly R4HA peak of appropriate LPAR combinations (I.E. where the software product runs) and not based on individual product measurement.

Once a Defined Capacity LPAR is deployed, this informs WLM (Workload Manager) to monitor the R4HA utilization of that LPAR.  If the LPAR R4HA utilization is less than the Defined Capacity, nothing happens.  If the LPAR R4HA utilization exceeds the Defined Capacity, then WLM signals to PR/SM and requests that Soft Capping be initiated, constraining the LPAR workload to the Defined Capacity level.

If a user chooses a Sub-Capacity WLC pricing mechanism, they will be required by IBM to submit a monthly Sub-Capacity Reporting Tool (SCRT) report.  Monthly WLC invoices are based upon hourly utilization metrics of LPAR hardware utilization, where the software product executes.  The cumulative R4HA and bottom line WLC billing metric is calculated for each product and associated LPAR group and not based on individual product measurement.

Bottom Line: From a Soft Capping viewpoint, the customer only pays for WLC software based upon the Defined Capacity (DC) or Rolling 4-Hour Average (R4HA), whichever is the lowest.  So whether a customer uses Soft Capping or not, in all likelihood, there will be occasions when their workload R4HA is lower than their zSeries server MSU capacity.

So, at first glance, VWLC seems to provide a compelling pricing metric, based upon Sub-Capacity and a pay for what you use ethos, and so why wouldn’t an IBM Mainframe user deploy this pricing metric?

The IBM Planning for Sub-Capacity Pricing (SA22-7999-0n) manual states “For IBM System z10 BC and System z9 BC environments, and z890 servers, EWLC pricing is the default for z/OS systems, and Sub-Capacity pricing is always the best option.  For IBM zEnterprise 114, environments, AEWLC pricing is the default for z/OS systems, and Sub-Capacity pricing is always the best option.  For IBM zEnterprise 196, System z10 EC and System z9 EC environments, and other zSeries servers, Sub-Capacity pricing is cost-effective for many, but not all, customers.  You might even find that Sub-Capacity pricing is cost effective for some of your CPCs, but not others (although if you want pricing aggregation, you must always use the same pricing for all the CPCs in the same sysplex)”.

Conclusion: For all small Mainframe users qualifying for the EWLC (AEWLC) pricing metric, arguably this pricing mechanism is mandatory.  For the majority of larger Mainframe users, the same applies, although a granularity of adoption might be required.  IBM also have a disclaimer “Once you decide to use Sub-Capacity pricing for a specific operating system family, you cannot return to the alternative pricing methods for that operating system family on that CPC.  For example, once you select WLC you may not switch back to PSLC without prior IBM approval”.  However, the requisite contractual exit clause option does exist; the customer can switch back to the PSLC pricing metric.

Some IBM Mainframe users might object to a notion of Soft Capping, relying upon their tried and tested methodology of LPAR management via the number of CPs allocated and associated PR/SM Weight.  This is seemingly a valid notion and requirement, prioritizing performance ahead of cost optimization.

Conclusion: As previously indicated, with VWLC, SCRT invoices are generated upon a premise of the customer only pays for WLC software based upon the Defined Capacity (DC) or Rolling 4-Hour Average (R4HA), whichever is the lowest.  So the VWLC pricing mechanism should deliver a granularity of cost savings, typically higher for a Soft Capping environment.

Some IBM Mainframe users might just believe that nothing can match their Parallel Sysplex Licensing Charge (PSLC) mechanism, first available in the late 1990’s, which might be attributable to other 3rd party ISV’s who cannot and will not allow for their software to be priced on a Sub-Capacity basis.  In reality, adopting the VWLC pricing mechanism delivers ~5% cost savings when compared with PSLC, as indicated by the IBM Planning for Sub-Capacity Pricing Manual (SA22-7999-0n) and related Sub-Capacity Planning Tool (SCPT).

Conclusion: Adopting Sub-Capacity based pricing metrics can only be a good thing.  If your 3rd party ISV supplier doesn’t recognise Sub-Capacity pricing, whether MIPS or MSU based, perhaps you should consider your relationship with them.  Regardless, the z10 server was the last IBM Mainframe to incorporate the “Technology Dividend” solely based on faster CPU chips.  The lower cost WLC pricing metric is now only available with the AWLC and related (E.g. AEWLC) pricing metrics, as per the z196, z114 and zEC12 servers.

Some customers might state that there is a lack of function or granularity of policy definition for IBM supplied Soft Capping (E.g. DC, GCL) or Workload Management (WLM) techniques.  To some extent this is a valid argument, but wasn’t it forever thus with IBM function?  Sub-Capacity implementation is possible via IBM, as is Workload Management (WLM), Soft Capping or not, but should the customer require extra functionality, 3rd party software solutions are available.

The zDynaCap software solution from zIT Consulting delivers a “Capacity Balancing” mechanism, integrating with R4HA and WLM methodologies, but constantly monitoring MSU usage to determine whether CPU resource can be reallocated to Mission & Time Critical workloads, based upon granular customer policies.  The only guarantee in a multiple LPAR environment, for a Mission & Time Critical LPAR to receive all available MSU resource, Soft Capping or not, is to inactivate all other LPARs!  Clearly this is not an acceptable policy for any installation, and so a best endeavours policy applies for PR/SM DC, GCL and Weight settings.

Conclusion: z/OS workloads change constantly, whether the time of day (E.g. On-Line, Batch) or period of the year (E.g. Weekly, Monthly, Quarterly, Yearly) or just by customer demand (E.g. 24 Hour Transaction Application).  Therefore a dynamic MSU management solution such as zDynaCap is arguably mandatory, implementing the optimum MSU management policy, whether for purely performance reasons, safeguarding the Mission & Time Critical workload isn’t impacted by lower priority workloads, or for cost reasons, optimizing MSU usage for the best possible monthly WLC cost.

In conclusion, not considering and arguably not implementing z/OS VWLC related pricing mechanisms is impractical, because:

  • The VWLC and AWLC related pricing metrics deliver the lowest cost per MSU for eligible z/OS software
  • When compared with PSLC, VWLC related pricing mechanisms deliver conservative ~5% cost savings
  • A pay for what you use and therefore Sub-Capacity pricing mechanism, not the installed MSU capacity
  • If extra MSU policy management granularity is required, consider 3rd party software such as zDynaCap

Software cost savings are not just for the privileged; they’re for everyone!