System Upgrade | Part 1 : Overview of Zero Down Time Approach

Whenever we think about different downtime approaches

1.Standard Approach

2. Near Zero Downtime Approach 

3. Zero Downtime Approach

1 -> 2 -> 3 [Effort increases and Downtime decreases ]

So even if we say Zero Downtime Option it means you will surely have a very small downtime that is the business downtime ( Ramp Down Restart Ramp Up )

This will be a series of blog and this is part 1 of that blog.

All the technical downtime in Zero Downtime approach is shifted to the phase called Uptime on Bridge. This approach is generally available starting from SAP S/4HANA 2021 also includes the update of feature or support package stacks within SAP S/4HANA 2020 also SAP S/4HANA Foundation 2020 (not allowed as standalone but only as foundation in combination with a defined list of add-on product version )i.e. ZDO can be used as a Standard feature.  

Note :- ZDO is not applicable for system conversion 

SAP S/4HANA supports add-ons from different vendors like SAP or 3rd party:

1. Standard add-ons delivered by SAP for SAP S/4HANA

2. Add-ons delivered by SAP Innovative Business Solution Organization (former SAP Custom Development)

3. Partner add-ons

So what happens is instead of going in technical downtime you go into uptime bridge. The transition to the uptime bridge  happens seamlessly by the administrator running the Support Package Manager.

In order to improvise , At the end SAP asks for your feedback and statistical data on SUM run , encapsulated in a file UPGANA.XML.

Why do we need to have Zero Downtime Option of SUM ?

To optimize the planned downtimes [technical downtime only that is already discussed above, but even the business downtime is significantly reduced] that are used for maintenance events like upgrade, feature or support pack updates. All phases are executed during uptime processing.

SUM phases that causes the long technical downtimes are:-

Table Conversion and DDL execution phase PARCONV_G

Main Import - phase TABIM_UPG

XPRAs XCLAs and AIM execution - phase XPRAS_AIMMRG

If we talk about con it would be , we need higher efforts in time of functional validation as well as project planning.

Required SAP Notes for ZDO

Prerequisite is SAP NOTE : 2707731 (Add-on products that are supported , can be checked here)

Execute and Monitoring Note : 3071115 [Will change with all the support packages]

For S/4HANA Foundation 2020/2021 : 291212919 / 3015497

SAP S/4 HANA compatible Add-ons : 2214409 (not all addons are available for zero downtime compatibility, but SUM is equipped with an automated check on addons)

Option of SUM : Comes with standard tools for software maintenance, no additional license required.

Database Space Requirements : Footprint in rather small compared to entire database is cloned , Instead only selective tables are cloned (based on changes to be performed with the maintenance event)

Downtime = Single restart: DB however is not restarted of the application servers , Restart takes approx 5 - 10 mins depending on the number of Application servers.

Stay tuned for follow up on this topic