Near-Zero Downtime Maintenance for SAP Business Suite Systems
Improvements of downtime minimization capabilities for Software Update Manager (SUM)
The downtime minimization feature nZDM for SUM has been general available for some months.
After a very successful period of controlled projects on customer site all over the world this feature is now included in the Software Update Manager 1.0 (SUM). Until it was shipped with SP7 it has been used on customer side in more than 150 executions, 40 productively. It is a main improvement to reduce the business downtime significantly.
The nZDM feature in SUM is still considered for continuous improvement activities.
What do you have to invest?
There are no separate license fees for using the downtime minimization capabilities of SUM. SUM is part of the SL Toolset and the newest version can be downloaded from the SAP Service Market Place.
This document describes the new available feature and the benefits you can expect regarding downtime optimization of SUM. It will be regularly updated to keep you up to date.
Benefits of nZDM for SUM
In SUM you have the option to use one of the following pre-configurations:
- “Single System” = no use of shadow instance (update) or shadow instance runs exclusively (upgrade)
- “Standard” = similar to EHPi or SAPup
- “Advanced” = intention to minimize the downtime
In SAP’s Software Update Manager (SUM) the advanced pre-configuration mode is used for extensive downtime optimization. Using the shadow instance for the main import (nZDM for SUM) is the main option in the “advanced” pre-configuration mode.
For further details about the shadow instance in SUM, see SCN blog http://scn.sap.com/community/it-management/alm/software-logistics/blog/2014/04/02/sum-introduction-to-shadow-system
Considering all downtime minimization capabilities which are offered in the advanced pre-configuration mode of SUM you can select the following capabilities:
- Intensive use of parallelization for Batch processing, DDL processes and R3TRANS
- SGEN in the shadow instance
- Customer transports import
With this feature, you consider the customer transports of your target release to the SUM procedure. The business downtime is reduced because repository related customer transports are imported during the uptime phase. In combination with nZDM the customer transports import can be used to execute z-table conversions in uptime.
The customer transports import is fully integrated with SPAU / SPDD, Transport Management System (TMS) and Change Request Management (ChARM). For further details please read SCN Blog: Import of customer transports for upgrades and customer releases available in SUM
When you use customer transports in SUM the screen to maintain SPAU and SPDD transport is not needed anymore. The procedure knows which of the transports are SPAU transports or SPDD transports. This also means that you can use as many transports for SPAU and SPDD as you want.
- nZDM for SUM
You can select which capabilities you need, the features are optional.
How to activate the offered downtime minimization capabilities?
nZDM for SUM can be used to apply Support Packages, applying enhancement packages (EHP) or to upgrade an ABAP-based SAP Business Suite or SAP NetWeaver system.
Which improvement can you expect when nZDM is used in SUM?
The downtime minimization benefit depends on the level of your update. An update of ECC 6.0 EHP1 to EHP7 is much more benefitial than an SPS implementation of SP9 to SPS10. Therefore the main focus of customer activities is on EHP implementations or upgrades.
Based on the already made experiences on customer site nZDM for SUM enables a minimum downtime of around 2:30h – 3:00h when implementing an EHP or running an upgrade.
The overall technical downtime (= minimum downtime + post-processing) is reduced significantly although the post-processing phase is extended due to the nZDM feature to around 0:45h – 1:00h
So in total we have an overall technical downtime of 3:15h – 4:00h
Just compare it with your key figures of your last EHP update.
Please find below 4 examples from real customer projects and a comparison between the overall technical downtime with SUM without nZDM or EHPi and SUM with nZDM:
As you see all the data we got are roughly 2 years old. At this time we offered nZDM of SUM on request and so we got a very good overview about working in different system environments and sizes.
After available on request we get feedback only based on the SUM upgrade info that are sent to us
Based on our experiences the technical downtime reduction seems to be stable and independent from database or data size as nZDM for SUM was tested by big customers as well.
The following measure shows an internal comparison between SUM for SAP ERP 6.0 with and without nZDM for SUM.
Also in this example the technical downtime is reduced > 55%!
Additionally you see that the overall project time is increased to approximately 20-30%. This additional time is used during the phases which are running in uptime. This has to be considered in the cutover plan.
How does nZDM for SUM work?
The nZDM capability of SUM uses the shadow instance for the main import.
Quick facts about nZDM for SUM:
- Introduces the “Record & Replay” technique for business transactions based on database trigger technology
- Minimizes manual effort: all steps run automatically in background
- Minimal additional hardware requirements due to shadow-technique, only additional DB space needed (80 – 350 GB)
- The additional DB space is needed for the transferred tables to the shadow (30 – 150 GB) and for logging tables (50 – 200 GB).
- When you want to use nZDM in combination with customer transport requests import you have to consider z-tables for table conversions in addition
- Available for all ABAP-based Business Suite products
Record & Replay means that the database changes during uptime of the maintenance process create triggers, which records the changes. The recordings are only needed for tables which are used for the update / upgrade in the shadow. With the help of the recording the shadow tables will be updated after the upgrade/update phases in the uptime. The majority of the recording updates are run in the uptime. Only the delta (last 10%) has to run just before the switch in the downtime.
What are the consequences for CPU and memory consumption?
You maintain the amount of process which are used by the Record & Replay technique (CRR). The default value for the amount of processes is three. This is the value which is recommended from our side based on the experiences we made with our customers. I am not aware of an impact on pereformance for the enduser.
nZDM can be used for common used databases with the following minimal versions:
- IBM DB2 LUW 9.7 FP4
- Oracle 10g
- MS SQL 2005
- IBM DB2 for z/OS 10.1
- SAP Max DB 7.9
- SAP HANA 1.00.52
- SAP Adaptive Server Enterprise (ASE)
- DB2 for IBMi 7.1
SUM allows using the nZDM capabilities for the following standard software maintenance activities:
- Applying a Support Package on any ABAP-System with a target release based on SAP NetWeaver 7.0 EHP 2, SP8 or higher
- Installing an EHP on top of any ABAP system with a target release based on SAP NetWeaver 7.0 EHP 2, SP8 or higher
- Upgrading your system to any ABAP system with a target release based on SAP NetWeaver 7.0 EHP 3 or higher
For further operational details please see SAP Note https://css.wdf.sap.corp/sap/support/notes/1678564.
nZDM is described in the official user guide of SUM as well.
When you are looking for additional support please also check the frequent asked question document:
What is new with SUM 1.0 SP14 – SP16?
In the past you probably got issues with nZDM that for example the replication rate showed 95% but the SUM didn’t accept this.Or you got issues due to very big tables to be copied.
With the latest SUM SPs we optimized nZDM:
- excluding big tables (sapup parameter)
- copying improvements to optimize the runtime for “copy to shadow” phase
- optimizing of CRR handlingfor transaction CRR_CONTROL
- optimizing of nZDM runtime
When you need to copy big tables (SAPor custom tables) to the shadow instance you should be aware of a parameter explained in the SAP note 1678564.
The default exclusion value is 50 GB.
If you want to mainly run conversions you probably didn’t need this feature. You disable the the maximum table size feature using the SAPuppar parameter set_max_tab_size = OFF.
In older SUM versions it sometimes happened that the refresh of the CRR_CONTROL was very time consuming due to high load of CR entries. The threshold was not accurate. This has been changed with the new SUM 1.0 SP. For this a “Cut-Off” Limit (“Maximum Logtable Row Count”) is introduced. This threshold ensures that the calculation is not such time consuming.
With the next SUM SP17 we plan to improve the start / stop procedure to avoid conflicts.