3. Parallelism & Slowness on TABIM_UPG & TABIM_SHADOW_UPG - Let's tick it

One of the top issues which we will face during SUM will be slowness/long running TABIM_UPG especially on stage MAIN_SHDINST/TABIM_SHADOW_UPG1.

It applies all kind of SUM runs - Upgrades, Migrations, Conversions. TABIM_UPG deals with R3trans process counts for faster completion.
 
Usually, we will be proceeding on default values of R3trans and others. However, we might need to increase during TABIM_UPG due to slow performance/progress via SUM Utilities.
 
✨We can set as same as CPUs count explicitly available for the server (Not shared pools)
 
How R3trans increase works?
 
SUM will set mainimp_proc parameter count (Master) automatically based on the R3trans process provided(with tp splits). It will reflect immediately and take effect on TABIM_UPG stage (in Next Operations/Process - Updates seen on var/SHDUPGIMP1.TPP)
 
Consider my scenario (faced from my end), My TABIM_UPG too slow on copying shadow tables SAPKLES618GAERP* in which by default SUM selected with 8 R3trans (4 * 2). I have changed to 16 since I have 16 CPUs (dedicated) which speed up the process and completed soon.
 
Here, Below can be applied automatically by SUM (Info shown in SUM frontend as well)
 
mainimp_proc - 2 (2 * 8 = 16, 2tps be assigned. Each tp will have 8 R3trans process)
parallel - 8
 
OR (Chosen by SUM for my scenario)
mainimp_proc - 4 (4 * 4 = 16, 4tps be assigned. Each tp will have 4 R3trans process)
parallel - 16
 
OR It can also be 8 (8 * 2 = 16)
 
NOTES:
 
1) 🌟Increasing the parameter will reflect in next table copy/progress/operations only. Current progress still runs with the older count. If we have already in last step, then increase in r3trans process has no effect.

2) Maximum Recommended is 50. If we have 16 CPUs, Set 16. If we have 64 CPUs, Set Max 50 only.

3) We will face huge impact if wrong/incorrect parameter provided (Say 17/32/500 R3trans instead of values <=16 in my case). If we provide incorrect values and it got reflected in live run since current process completed, then SUM will run with ONLY 1 R3TRANS process / By luck - Use default. If its 1, then completion will take 3-5 days for that table (current process). I did this mistake and regretted the mistake.

Refer below notes for reference.

Note 1616401 - Parallelism during upgrades and implementations vers34

Note 1127194 - R3trans usage with parallel process - we can also set before starting SUM vers20

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