The post provides a high-level overview of the challenges to be considered when applying the Scrum delivery framework to larger scale projects. Scale in this context relates to the size of the product being delivered; one product only. Scale here does not relate to multi-product deliveries, distributed team considerations, technical complexity or user concurrency. The term product could relate to a software product, a service or indeed any tangible outcome. The Scrum framework is used worldwide in a wide variety of contexts including fighter aircraft development, farming and education in the classroom.
In essence the Scrum agile framework is founded on the idea that self-empowered, cross-functional teams delivering working product increments in business priority order produce a better outcome in a quicker timeframe than would otherwise be achievable. There’s considerably more to Scrum than this statement affords, however for brevity this context sufficiently sets the scene.
In practice many implementations dilute the value of the Scrum framework by introducing elements of traditional Waterfall style linear process; such hybrid projects are often a disaster as aligning two process model takes discipline and care, in most hybrid cases the very opposite is true. As such the real value of Scrum is achieved through adherence to the framework in its entirety; subjective preference and selective pick-and-mix type implementations are fraught with risk and equally inefficient. Scrum has key advantages over many frameworks in this respect; the principles and practices are clear, short and intuitive and therefore the learning curve is short and initial adoption straightforward.
Before moving to discuss the main topic of this post i.e. Scaling Scrum, it is worth considering the basic mechanics of the Scrum flow.
1. A Product Owner manages a product backlog of user stories prioritised by business value; the higher priority the more detailed the story may be. Lower priority stories may be very high-level and are referred to as epics.
2. A ScrumMaster supports an empowered team to deliver a set of stories within a set timeframe, i.e. sprint cycle. The definition of delivered (or done) is agreed up front but typically equates to production quality working software that satisfies user defined acceptance criteria. The ScrumMaster ensures the team is focused on a defined sprint goal and resolves obstacles.
3. During a sprint the team synchronises on a daily basis during a stand-up meeting; team members make commitments not to the ScrumMaster but to their peers.
4. After each sprint cycle a retrospective meeting is held to inspect and adapt the process.
5. On a continual basis the Product Owner inspects and adapts the user stories on the backlog – adding emerging detail.
6. One sprint leads to the next on iterative basis within the context of a release.
The main sprint artefacts are the Product Backlog (whole-product) and Sprint Backlog (agreed stories for a sprint cycle). Velocity reports are also significant in terms of understanding how accurate estimation has been and how productive the team are.
The typical Scrum team size should be in the 4-8 region a larger team can detract from effective communication and add risk to adoption of the Scrum values of Focus, Courage, Openness, Commitment and Respect; all of which work better in a small team setting. Additionally the Scrum events (ceremonies) start to become less effective the bigger the audience. This is true for any two-way collaboration; effectiveness is inversely proportionate to audience size. And so, if the optimal Scrum team size is less than 10 yet the framework is applicable to large, complex project delivery how does Scrum scale?
Scaling Scrum – Challenges
Before considering approaches to Scaling Scrum it is worthwhile first to consider some of the key challenges likely to be encountered.
1. Focus. The level of difficulty in maintaining an effective product backlog is linear to the scale of the product. Scrum requires a whole-product mindset; the bigger the product the more challenging this can become.
2. Communication. Sub-dividing a larger project across multiple Scrum teams introduces communication boundaries. Face to face communication, a key Agile principle, can be difficult to maintain. More teams typically means more time spent on synchronisation (i.e. communication), this overhead is unavoidable.
3. Interdependency. Product backlog items are seldom standalone concerns with no interdependencies. Interdependencies can be managed effectively within a single team environment, for a multi-team environment interdependencies introduce process overhead.
4. Empowerment. Perhaps a more human factor than the preceding points but important nonetheless. Multiple team environments reduce the empowerment of the single team. This can impact upon the motivation and courage of the team as consideration (respect and so on) to other teams becomes a factor. Empowerment in this context is therefore limited in a manner not encountered by a single team.
5. Scrum thinking. Scaling challenges can often result in non-Scrum practices or adaptations creeping in. This can be perception related “Is Scrum still appropriate?” or a lack of confidence in respect to how to approach the problem in the face of proven linear alternatives.
Scaling Scrum – Typical Approach
A typical approach to Scaling Scrum is to sub-divide the product backlog into themes (or features) and to introduce a Scrum team per feature, i.e. a Feature Team.
1. Focus. Ideally each Feature Team would have a dedicated Product Owner perhaps operating within a Product Owner hierarchy with a Chief Product Owner at the top. The whole-product mindset requires a single product backlog, multiple product backlogs would require cross-prioritisation and as such the approach offers no value. To ensure manageability each Product Owner will have feature specific views on the product backlog. Feature rollups will also be added to provide Product Owners at higher levels of the hierarchy with a summarised view. Also in relation to manageability epic user stories play a big part in keeping the size of the product backlog within the 100-150 region.
2. Communication. A new Scrum event is introduced; the Scrum of Scrums. In short this meeting is focused on the discussion of dependencies and related problem solving. The regularity, duration and attendees for the Scrum of Scrums is not prescribed, instead need should drive all such factors. As with many aspects of Scrum, the Scrum of Scrum meeting can be hierarchical; for example groups of teams of related features may have a Scrum of Scrum meeting, selective attendees of which may attend a higher level Scrum of Scrum meeting at the product level. Release kick-off meetings and shared team members (perhaps on a cycle) are other effective means to make cross-team communication integral to the process. On very large, or very complex projects dedicated integration teams can be introduced to ensure communication and dependency challenges are de-risked.
3. Interdependency. In addition to the communication and resolution of dependency activity occurring within the Scrum of Scrum meetings, look ahead planning is often implemented. This approach requires that a rough idea of the backlog items for the subsequent 2 sprints are tentatively identified during each sprint planning meeting. Historical average velocity can help in terms of sizing. With an indicative view of the sprint backlog well in advance dependencies can be identified and discussed well in advance.
Large Scale Scrum with LeSS
LeSS (Large-scale Scrum) is comprised of 2 scaling frameworks that extend Scrum; basic LeSS supports up to 8 teams, LeSS Huge supports scale into the thousands of participants on a single product delivery. In both cases LeSS provides an approach to scaling that is Scrum in both principle and practice.
The LeSS framework is founded on the principle of whole-product focus; one overall Product Owner manages a single product backlog that is delivered by 2-8 teams each with a ScrumMaster. In this context, the scaled Product Owner is supported by multiple teams working directly with customers, business users and stakeholders. On larger scale products the Product Owner role will be focused more on big-picture prioritisation rather than detail clarification; supporting teams will perform the latter. LeSS Sprint cycles are aligned across all teams and whilst each team manages their own sprint backlog one and only one potentially shippable product increment is delivered. The Sprint planning event in LeSS is split into 2 defined events; Sprint Planning One (2 hours) where all teams collectively determine the backlog items for the sprint and Sprint Planning Two (2 hours) where an individual team (or multiple teams working on a common feature) define how the stories will get to done. The Sprint review event is the same in LeSS as single-team Scrum, but an additional Overall Retrospective event is added to provide 2 cycles of process inspection and adaptation; team-level and then product. The approach to communication and interdependency management is left at the discretion of the teams involved however guidance is provided in respect to observer attendance at team Daily Scrum events, multi-team meetings, Scrum of Scrum meetings and the use of Open Space and Continuous Integration techniques.
LeSS is not only a collection of principles and practices but also a process framework with a concrete set of rules (updated February 2020) to guide application.
LeSS Huge provides framework support for product deliveries beyond the 8-team limit. The LeSS Huge approach starts with categorisation of the product backlog into requirement or development areas, each with a dedicated Area Product Owner who has an area specific view onto the overall product backlog. Sub-division by requirement areas is customer-focused, sub-division by development areas focuses on the architecture of the product. In either case each individual area can be considered a scaled-up feature team which will be delivered by a (basic) LeSS implementation with up to 8 teams. With LeSS huge sprint cycles are aligned across all areas and a single product increment delivered, not one per-area. Sprint review and retrospectives are held at the area and product levels.
LeSS Huge is a significant undertaking and will have a long adoption cycle.
In conclusion the LeSS frameworks provide a structured, empirically validated extension to Scrum to support product delivery at scale. Given the increased risk LeSS implementations should be guided by expertise and experience with the LeSS principles, framework and rules. The Certified LeSS Practitioner certification and related course should be considered as part of any process risk mitigation strategy.
Scrum@Scale is a framework for multiple Scrum Teams, authored by Jeff Sutherland, which is designed to be lightweight and based on Scrum principles and values.
Scrum@Scale contains two cycles which separate accountability for how work is done from what work is done; the ScrumMaster cycle and the Product Owner cycle. This clear separation reduces organisational conflict and provides the basis for optimal productivity and the coordination of combined effort toward a single goal.
The ScrumMaster cycle (the how) focuses on continuous improvement, impediment removal, cross-team coordination and deployment. The Scrum@Scale framework uses Scrum of Scrum (SoS) principles to organise multiple Scrum teams working together to deliver an integrated set of product increments at the end of every Sprint. A new role, the Scrum of Scrums Master is accountable for the delivery and communication aspects of the combined Sprint, an impediment backlog is introduced to prioritise impediments across coordinating teams. A Scaled Daily Scrum Event is attended by representatives from each team to ensure synchronisation on impediments, dependencies and improvements.
The Product Owner cycle (the what) focuses on strategic vision, backlog prioritisation, decomposition and refinement and release planning. The Scrum Product Owner role is expanded to a Product Owner Team which is responsible for communicating the strategic vision for the product, business alignment, prioritisation of a single product backlog and release planning. A new role, the Chief Product Owner coordinates priorities with the Product Owners that work with each Scrum team within the Scrum of Scrums.
Scrum@Scale introduces two new executive teams. The Executive Action Team serves as the organisation level ScrumMaster with overall responsibility for impediment removal and process quality and continuous improvement. The Executive MetaScrum Team fulfills the organisation level Product Owner role with overall responsibility for aligment to strategic priorities. The Executive MetaScrum Team holds a stakeholder alignment meeting every Sprint; the MetaScrum Event. This event provides an opportunity to make strategic decisions that affect the entire organisation. The Chief Product Owner presents the Product Backlog to the Executive MetaScrum Team in order to support decision making in respect to strategy, funding, resource planning and customer, market or regulatory commitments.
The ScrumMaster cycle and Product Owner cycle have two touchpoints; team level process and product/release feedback. The former simply relates to the non-scaled Scrum process where the team self-organises to improve the velocity by which product backlog items are delivered in a releasable state. The latter relates to continuous improvement in two areas; product feedback impact on the product backlog and release feedback impact on the deployment process. For both touchpoints metrics (improving velocity, quality, team happiness etc.) and transparency (absolute honesty) are key to success.
In conclusion Scrum@Scale follows a scale-free architecture where there are no artificial constraints applied and scaling can follow an organic path, based on actual requirements and time-scales. Whilst simple in concept, the practical application of Scrum@Scale will require significant commitment at all levels of the organisation.