Today, customers expect that cloud solutions should offer continuous availability, sparing them the need to wait for planned maintenance events. They prefer that software deployments do not disrupt their businesses anymore. And this is exactly what Blue-Green deployment methodology helps SAP S/4HANA Public Cloud achieve.
With the current Blue-Green deployment supported updates (hotfix) and upgrades (release) for ABAP based cloud systems, SAP S/4HANA Public Cloud aims at 5 min or less downtime. This number is planned to be reduced further down to zero.
This blog post aims to introduce you to this blue-green deployment methodology used in SAP S/4HANA Public Cloud updates or upgrades and discuss what all features and functionalities are made available to users even when the update or upgrade is running. So, let’s begin!
What is Blue-Green Deployment?
Blue and Green simply refer to two runtimes on different versions. As shown in the below diagram, Blue is the currently active production runtime and Green is the updated or upgraded version which would eventually replace the Blue one.
Blue-Green deployment works like this: the consumer uses the blue runtime; a green runtime is deployed in parallel. Then, the consumers are switched to use the green runtime and the blue runtime is removed. In above diagram, ‘Preparing V2’ and ‘Switching to V2’ stages represent the Update or Upgrade phase.
As simple as that!
What it means is all the changes in an update or upgrade are deployed without interrupting the user for much duration. After carrying out most of the update/upgrade related tasks in the background, the system simply switches to the updated runtime and the updated system become available. Thus, the downtime experienced by the user, during which logging into system is not allowed, is reduced via Blue-Green deployment.
Currently, all the systems in 3SL (3 System Landscape) and only Production system in 2SL (2 System Landscape) in SAP S/4HANA Public Cloud are updated or upgraded using Blue-Green Deployment.
Why Blue-Green Deployment?
Blue-Green deployment paves path for zero downtime deployment. This facilitates multiple advantages such as:
Continuous business operations since update or upgrade changes are applied without delays.
Innovations can be deployed more frequently in small increments as business disruption due to downtime is avoided.
Risk of change is minimal. In case the update or upgrade fails, it is relatively easier to switch back to previous version and update or upgrade can be re-triggered at later point of time once it is fixed.
What is Downtime and Limitation Period?
Downtime is the period during the update/upgrade when a business user cannot log into their SAP S/4HANA Public Cloud system. This is the reason downtimes are considered disruptive. On the other hand, Blue-Green deployment accomplishes much of its update or upgrade related tasks during Limitation Period. Now what is this Limitation Period?
Limitation Period is a timeframe in which non-disruptive restrictions that ensure parallel execution of the maintenance are applied. This means that a business user is allowed to log into and perform certain functionalities even when the update or upgrade is going on in background; although with some restrictions in place (more on that in further sections).
For 2SL Production system updates, limitation period starts about 12 hours before maintenance period mentioned in 2SL Maintenance Schedule.
For 3SL Starter and Development system updates, limitation period starts about 6 hours before maintenance period mentioned in 3SL Maintenance Schedule.
For 3SL Test and Production system updates, limitation period starts about 12 hours before maintenance period mentioned in 3SL Maintenance Schedule.
For 2SL Production and all 3SL systems upgrades, limitation period starts about 32 hours before maintenance period mentioned in 3SL Maintenance Schedule.
What does Limitation Period allow or restrict?
Logically, the next question to follow is – which functionalities are allowed during the limitation period, and which are blocked.
To maintain consistency across the systems, it is important to put some restrictions around which functionalities are available during the limitation period. E.g. - certain system specific functionalities and business transactions including executing existing workflows, maintaining current settings etc. are available during blue-green limitation period; whereas other functionalities like release transports, data migration etc. which can affect the consistency across systems are blocked.
Below is the detailed information regarding availability of important functionalities during the limitation period of blue-green deployment of a new update/upgrade based on the customer landscape:
- Role Creation and Assignments
This refers to role creation via Manage Business Roles app; and role assignment via Manage Business Users app.
- Workflows and Attachments
This includes creation of new workflows, and execution of existing workflows/attachment functionalities.
- Transportable Configurations
This refers to those configurations done via CBC Activities (or Implementation Activities app in 3SL) that can be captured in a Transport Request and pushed to further systems. This includes all configurations which are not ‘Current Settings’.
- Number Range Current Settings
These are the number range related current settings done in the SAP S/4HANA system.
- Non-Number Range Current Settings
These are the current settings that are not number-ranges and cannot be captured in a transport request and need to be redone in Production System.
- Custom Development
This refers to Custom Development that can be done in 3SL systems via ABAP Development Tool.
- Central Business Configuration (CBC) Project
Access to the projects created in CBC system.
- Change Project
Creation of a new change project by initiating a change in the project.
- Add New Country/Scope Extension
This functionality refers to initiating a change in project to add a new country to the scope or additional scope items.
- Organizational Structure creation and changes
This functionality refers to initiating a change in project to create or edit the organizational structure.
In-App and Side-by-Side extensibility done in SAP S/4HANA Cloud.
- Test Automation Tool
Test Automation Tool is used in SAP S/4HANA Cloud to automate business process testing in the Quality/Test system.
Transport release and import in SAP S/4HANA systems during blue-green deployment Limitation period.
Forms creation and editing in SAP S/4HANA Output Management in SAP S/4HANA Cloud systems.
- General Ledger
This refers to any changes made to General Ledger.
- Data Migration
Data Migration done via Data Migration Cockpit application.
Blue-Green deployment helps to safeguard SAP S/4HANA Cloud customers from business disruptions during updates/upgrades. Awareness regarding restrictions in place during limitation period of Blue-Green deployment will empower customer with clarity about what activities can be continued with even during the updates/upgrades. This would further lead to an overall better experience for SAP S/4HANA Cloud customers.
The slightly restrictive nature of the short limitation period (instead of longer downtime in traditional deployments) in turn helps to reach the goal of reduced business downtime of the Production system, which is a key capability of any Cloud ERP.
Hopefully, this blog post would help you in understanding and overview of Blue-Green Deployment in context of SAP S/4HANA Cloud and how this would impact you as a user during updates and upgrades.
Below are some important links for further information regarding Blue-Green Deployment and maintenance schedules in SAP S/4HANA Cloud: