In this blog, I would be sharing the details about the SAP S/4HANA upgrade from 1809 to 1909 using ZDO of SUM tools and lessons learned as part of Proof of Concept - PoC
Introduction
Lessons learned from ZDO Proof of Concept Scope
Following is the execution rundown of critical ZDO phases with runtimes
As a result of the POC, the ZDO option took just 4 minutes of app servers to restart time to move from SAP S/4HANA 1809 over to the target release SAP S/4HANA 1909.
Like any other upgrade, ZDO of SUM will go through all the initial phases of the regular SUM tool. For example, Extraction, Configuration, Checks, Shadow Instance, Repository Lock, and SPDD on Shadow. Logically technical ZDO phase starts from the middle of the Preprocessing phase.
ZDO Impact analysis:-
A detailed impact analysis was performed to identify the read-only table and cloned tables with the highest change rate for the duration of bridge time. Identified critical restrictions were addressed with the support of the SAP development team in the form of SAP notes.
Overall, no significant tables were identified under read-only tables. Refer for more details about impact analysis Impact Analysis as part of Software Update Manager 2.0
ZDO User Rollover to Bridge:-
After all the technical preprocessing activities, the users on the sandbox system are rolled over successfully without any interruption to their regular transactions. However, the user rollover phase took around 34 mins due to known issues HANA DB user store. The user store should be shared globally. However, if the user store is located on a local drive, it’s important to consider the steps outlined in the central SUM SAP Note for SAP HANA. For the latest SUM 2.0 SP09, it’s SAP Note 2935077.
ZDO Uptime on the Bridge:-
Users were on the bridge instance for about 27 hours without any interruption to their regular business transactions. While the upgrade is running, in the background, SUM upgrade phases are executed for 15 hours.
App server Restart by SUM:-
After 15 hours of upgrade phases execution, the SUM informed the basis team that upgrade downtime phases are completed and ready for the restart of the application server to move to the target release. Since the completion popup arrived at midnight. The application server restart executed during the working hours.
SUM tool took 4 mins to restart the two application servers. This is the only time where the system was not available for any use.
Note:- the above-mentioned numbers are SUM execution runtimes. No dialog times(inputs, SPDD, SPAU, issues resolution, ramp down, ramp up ect…) are not counted.
Post Processing:-
The new SUM tool came up with the option to continue the SUM post work with business validation. The same has flowed in the POC. This is a generic SUM capability introduced very recently.
ZDO Specific SUM screens :
Note: Following screens are based on the SUM 2.0 SP8 PL 03. You will only find ZDO specific screen that impacts ZDO processes. You can find generic SUM screens in many SAP blogs.
Generic Stack XML screen
ZDO option is available only as a Pilot at the time of this blog. Please refer to SAP Note 2707731 and ZDO Blog for the latest information. To enable this option in the SUM tool you need to register, and magical key provided by the ZDO product manager after checking the feasibility.
You will start seeing the ZDO option on the SUM tool header as a select upgrade method for the current upgrade.
If there are any SLT triggers on the current system ZDO of the SUM tool request the RFC connection to the central system to handle the SLT triggers as part of processes.
Please check blog SAP blogs for more details on SLT trigger handling with Software Update Manager 2.0
Silent Data Migration is a new concept introduced starting from S/4HANA 1909 and higher and this does not depend on the SUM tool rather it is triggered depending on the target release.
For more details please check the blogs Silent Data Migration and Monitoring Silent Data Migration
Shadow instance number: Once all the shadow instance phases are completed SUM tool uses the Shadow instance number for running the downtime relevant phases while the users are transacting from the bridge instance.
Impact analysis: When using the ZDO users might see certain impacts on tables and additional database space when they are on the bridge instance. Using the impact analysis, you can identify the potential impacts with respect to the production cycle in the POC itself. This will help the customer to decide whether to move on with ZDO or not.
For more details please check SAP blog Impact Analysis
User Roll-Over to Bridge system – 1st screen
Very important ZDO phase. You will see the screen when all the ZDO preparatory steps are completed and the SUM tool is ready to enter the upgrade downtime and roll users to the bridge phase.
When you click next on this SUM screen, all the users will be rolled over to bridge instance without any disruption and seamlessly.
User Roll-Over to Bridge system – 2nd screen
Once all the sessions are successfully connected to the bridge instance SUM stops at the screen to provide confirmation. You will not see this screen in case if you have any issues with any session.
Here onwards all the users will logically be connected to the bridge instance and continue to execute the regular transaction from the bridge instance. Underneath SUM will continue and execute upgrade phases.
User Roll-Back to Original – 1st screen
Once all the downtime upgrade phases are completed SUM will stop at this screen to let you know that all the upgrade downtime phases are completed and ready for the app server restart.
In the production cutover, you will continue to be on the same screen till you reach the planned downtime usually Friday night. On a cutover day, first, you continue with Ramp down and click next on SUM tool. SUM will restart the application serves.
User Roll-Back to Original – 2nd screen
You will see this screen after all the application servers are restarted along with few other SUM phases.
After the restart, you will be on the target release and you should be able to continue with POST steps like SPAU etc..
Hold the SUM till you complete Post work
This is a new feature recently introduced in the SUM tool to parallelize the post-processing time of the SUM tool. In this phase, you can pause the SUM execution and continue with post-work basis work (exp SPAU, Post transport import, configuration, etc..). After you are done with post-work, you can execute the SUM post-processing phase while business validation is going on.
Well, this is the SUM completion screen. However please note that the upgrade is not completed.
You need to complete the new S/4HANA upgrade feature called Silent Data Migration (SDM ). The SDM is automatically triggered by the SUM tool and it will wait for you to execute BTCTRANS2 to release its background job SAP_SDM_EXECUTOR_ONLINE_MIGR.
For more details please check my SAP blogs Silent Data Migration and Monitoring Silent Data Migration
Let me repeat this one more time, SDM is independent of the SUM tool options(nZDM, ZDO) rather it depends on the target release of S/4HANA. They are executed after the upgrade and parallel to transaction usage on the target system.
In this POC following list of SDM classes executed after the upgrade using ZDO.
SDM Class Name for SAP S/4HANA 1909 | |
CL_CO_ESH_LONGTEXT_MAPPING | CL_SDM_QM_STXH |
CL_SDM_RFM_EBAN_SEASONS | |
CL_FINS_SDM_ACDOCA_NETDT | CL_SDM_S4PPM_PROJECT_DATE_19A |
CL_NGC_CORE_SDM_CAWN | CL_SDM_SDBIL_VBRP |
CL_NGC_CORE_SDM_CLF_HDR | CL_SDM_STXH_CUP_CIG |
CL_SDM_ABCALTCNTL_CHARCASSIGN | CL_SDM_STXH_FIMX |
CL_SDM_ACR_ACDOCA_ACRVALDAT | CL_SDM_SWF_FLEX_PROC_01 |
CL_SDM_ACR_BSEG_ACRVALDAT | CL_SDM_SWF_FLEX_PROC_02 |
CL_SDM_BALHDR | CL_SDM_SWF_FLEX_TDRAFT_01 |
CL_SDM_BSEG_BR_BARCODE | CL_SDM_SWF_FLEX_TDRAFT_02 |
CL_SDM_BUPA_BPU_BP001 | CL_SDM_SWF_FLEX_TEMPLAT_01 |
CL_SDM_BUT0BK | CL_SDM_SWF_FLEX_TEMPLAT_02 |
CL_SDM_BUT0BK_V2 | CL_SDM_SWWWIHEAD_01 |
CL_SDM_POCR_CORRECT_COUNTS | CL_SDM_SWWWIHEAD_02 |
CL_SDM_POCR_CORRECT_KPIS | CL_SDM_SWWWIHEAD_03 |
Summary
Isn’t it really interesting to see a SUM tool with no downtime!! Or an upgrade to target release with a downtime of an application server restart!!
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