BI 7.0: Source System upgrade from R/3 Enterprise to ECC 6.0

Question

Background:
I am relatively new to BW team and will be going through my 1st source system upgrade.
We currently have BI 7.0 SPS 17 connected to source system R/3 Enterprise EP1.
We are upgrading to the source system to ECC 6.0.
In Development and QA Environments:
we will have access to both old (R/3 Enterpirse) and the new (ECC 6.0) source systems.
We have a opportunity to compare the BW Objects, data flow and data loading from
both source systems.
In Production, however, we will just upgrade over 3 days downtime.
One Question that comes to mind in this regard...
What sort of things, we should be checking for before and after upgrade in Dev/QA and in Prod environments and what tools are available that can help the analysis and validation process ?
Some of the suggestions that were given to me include following points.
Before Upgrade:
1 Check data, taking pre images of it for testing with post upgrade.
2. Perform proper analysis of Source system related BW objects.
  - A complete listing of actively used Datasources,.. etc.
3. Make delta queues empty,
Make sure that all existing deltas are loaded into BW.The last request delta must not deliver any data and must be green in the monitor.
4. Stop Process chains from BI (remove from schedule) and collection runs from R/3 side
After Upgrade:
1 After the OLTP upgrade, refer to note 458305 and other notes that are relevant to the actual upgrade
(depending on the R/3 system release / R/3 plug-in to BI plug-in compatibility).
2. Check logical system connections. Transactions SMQS, RSMO and SM59, If no access, then we can use Program RSRFCPIN_NEW for RFC Test.
3. Check and/or Activate control parameters for data transfer. SBIW ---> General Settings --->
Maintain Control Parameters for Data Transfer
http://help.sap.com/saphelp_nw70/helpdata/EN/51/85d6cf842825469a51b9a666442339/frameset.htm
4. Check for Changes to extract structures in LBWE Customizing Cockpit 
    - OSS Notes 328181, 396647, 380078 and 762951
5. Check if all the required transfer structures are active. See OSS Note 324520 for mass activation.
7. Check if all Source system related BW Objects are active - Transfer rules, Communication rules, update rules,DTPs,..etc. 
Below is a link for some useful programs in this regard.
https://www.sdn.sap.com/irj/scn/wiki?path=/pages/viewpage.action&pageid=35458
6. Test all important datasources using RSA3 and check for OLTP Datasources changes .
As soon as BW notices that the time stamp at the DataSource in the OLTP is newer than the one in the transfer structure, it requests replication of the DataSource and activation of the transfer structure. Transfer the relevant DataSources only if required, and transfer only the ones that have changed (RSA5 -> Delta).
7. Create Data flow objects (trnasfer rules, infopackages, trnasformations, DTPs) for the Replicate
new/changed datasources,if needed. 
8. Check all CMOD enhancements.
If we are using a customer exit with the extractor in the OLTP, see Note 393492.
7. Check for unicode (all custom programs or Function Modules for DataSources)
5.  Check all the queues in RSA7, start delta runs and test data consistency.
For delta problems:In the BW system, start the 'RSSM_OLTP_INIT_DELTA_UPDATE' program for the DataSource and the source (OLTP) system for which the init selections are then transferred from BW into the ROOSPRMSC and ROOSPRMSF tables in the source system so that the delta can continue.
9. Take back up of data posted during upgrade for contingency planing.
10. Run the entire set of process chains once if possible and let it pick up no data or the usual master data.
Since we have lot of experts in this forum, who have probably gone through such scenario many times, i wanted to request you to Please Please advise if i have stated anything incorrectly or if i am missing additional steps, OSS Notes, important details...

Answer 1

Thanks Rav for your detailed post and very helpful contribution by posting all the information you had regarding the upgrade.
We have similar scenario -
We are upgrading our source system from 4.7 to ECC 6.0. We have our BI system with BI 7.0 at support pack 19 (SAPKW70019).
Our strategy in ECC deployment  ->
In development we copied our old DEV 4.7 system DXX to new ECC system DXY (new system ID).
In production we are going to use same system PRXX upgraded from 4.7 to ECC.
Now we are in testing phase of ECC with all interfaces like BI in Dev.
My questions are below ->
How can we change/transfer mapping of all our datasources in Dev BW system BID to new ECC dev system DXY (Eg. Logical system LOGDXY0040) from Old dev system DXX (Eg. Logical system LOGDXX0040). We donot want to create new datasources or change all transfer rules/Infosources for old BW3.x solutions on our BI.
Also in new ECC sourcesystem copy  we see all datasources in Red in RSA7 transaction. Do we need to initialize again all the datasources from our BW BID system.
Is there any easy way for above scenario ?
Please let me know if you have any further helpful information during your ECC 6.0 upgrade connecting to BI 7.0 system.
I have found some other links which have some pieces of information regarding the topic -
Upgrade R/3 4.6C to ECC 6.0 already in BI 7.0
http://sap.ittoolbox.com/groups/technical-functional/sap-bw/sap-r3-migration-and-sap-bw-version-1744205
BI 7.0: Source System upgrade  from R/3 Enterprise to ECC 6.0
Re: ECC 6.0 Upgrade
Re: Impact of ECC 6.0 upgrade on BI/BW Environment.
ECC 5.0 to ECC 6.0 upgrade
Thanks
Prasanth