SAP MRP Run Time Simulator for ECC Classic MRP (MD01 and MDBT Jobs)
This simulator estimates how long a classic MRP run in SAP ECC 6.0 takes as an MD01 or MDBT background job, from the materials it will plan, your measured time per material and the number of parallel processes. Use it to decide between net change and regenerative runs and how much parallel processing a night window needs.
Your numbers
Measure: previous job runtime divided by materials planned, from the MRP list statistics or job log.
Your results
Estimate method: the mode, scheduling and efficiency factors are planning assumptions. Calibrate the milliseconds per material from your own job history.
MRP runtime vs parallel processes
Sweeps Parallel processes from 1 to 20, holding your other inputs fixed.
Want your MRP night window reviewed?
Send us job runtimes and planned material counts for a few runs and we will review the parallel processing and processing key settings for your plants.
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How classic MRP decides what to plan
Total planning in ECC runs per plant or scope of planning with MD01 online, or as a background job with MDBT, which schedules the same run with a variant. Which materials get planned depends on the processing key. NETCH plans only materials with a planning file entry flagged for net change; NETPL does the same but only within the planning horizon; NEUPL plans every material with an MRP type in the scope, regardless of the planning file. Planning file entries are written to DBVM when a relevant change happens, such as a new requirement, a goods movement or a master data change. Planning mode 1 adapts existing planned orders and requisitions; mode 3 deletes and recreates them, which costs more time and creates new numbers.
- NETCH: changed materials, full horizon
- NETPL: changed materials, planning horizon only
- NEUPL: all materials in scope
- DBVM: planning file entries driving net change
The formula and its basis
Materials planned = scope x net change share, or the whole scope for NEUPL. Serial runtime in minutes = materials planned x milliseconds per material x planning mode factor x scheduling factor / 60,000. The factors are planning assumptions: deleting and recreating data costs more than adapting it, and lead time scheduling reads routings for in-house items. Parallel processing divides the work by plant and low-level code packages across servers, but not perfectly, so effective parallelism = 1 + (processes - 1) x efficiency. Runtime = serial runtime / effective parallelism. The best input you can give is milliseconds per material from your own history: previous job duration from SM37 divided by materials planned from the MRP run statistics.
Worked example
50,000 materials in scope, 30% with planning file entries, NETCH, 120 ms per material, planning mode 1, basic dates: 15,000 materials planned, 30 minutes serial. With 4 parallel processes at 80% efficiency the factor is 3.4 and the runtime about 9 minutes. A weekly NEUPL run on the same scope with lead time scheduling and mode 3 plans 50,000 materials at 120 x 1.5 x 1.3 ms, about 195 minutes serial, or about 57 minutes with 4 processes. The chart shows diminishing returns: past roughly 8 to 10 processes, waits on low-level codes and locks usually limit further gain.
Parallel processing setup and MRP Live
In ECC, parallel MRP is configured in Customizing under Production, Material Requirements Planning, Define Parallel Processing in MRP (transaction OMIQ), where you assign the RFC destination or server group and the number of sessions, then set the parallel processing indicator in MD01 or the MDBT variant. Keep enough dialog work processes free on the servers you assign. MRP Live, transaction MD01N (program PPH_MRP_DISPATCHER), runs planning inside the SAP HANA database. It is the standard run in S/4HANA and is also shipped in SAP_APPL for Business Suite on HANA, so it only applies to ECC if the database is HANA; on ECC with Oracle, DB2, SQL Server or MaxDB, classic MRP with MD01, MDBT and MD03 remains the tool.
Frequently Asked Questions
How do I run MRP in SAP ECC?
For a plant, use MD01 (total planning) with a processing key such as NETCH, a planning mode and scheduling indicator, then check results in MD04 or MD05/MD06. For a single material use MD03. For a nightly run, schedule MDBT or MD01 in background with a variant, usually as one job per plant or scope of planning.
What is the difference between MRP Live and classic MRP?
MRP Live (MD01N) is the S/4HANA planning run that executes most logic inside the HANA database and plans across plants by material. Classic MRP (MD01, MDBT, MD02, MD03) runs in the application server and is the only total planning run in ECC 6.0 on a non-HANA database. MD01N needs SAP HANA, so on ECC it applies only to Business Suite on HANA.
Why does my MRP job take so long?
Typical causes are a regenerative run where net change would do, planning mode 3 deleting and recreating everything, lead time scheduling on all items, a large planning horizon, no parallel processing, and many materials with complex BOMs. Measure milliseconds per material over several runs and test the effect of each setting.
What are SAP MRP jobs and how should they be scheduled?
MRP jobs are background runs of total planning, created with MDBT or MD01 in background with a variant per plant or planning scope. Schedule them after the last goods movements and before planners start, chain dependent plants in sequence, and monitor them in SM37 like any other job.
If planners want to ask why a material was planned the way it was in plain English against ECC on your own servers, we can set up a private AI layer that reads the MRP results read-only.
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