How many SOLVE/Netmaster regions can we link and sync together?

Document ID : KB000108627
Last Modified Date : 30/07/2018
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Question:
We currently have 50+ LPARs spread over various business units.
Currently each business unit has its own group of regions linked and synced.
We want to join everything so we have two focals for all LPARS.

Would it be better to
- take all LPARS  and point them to 2 focal points, or 
- point each business unit to its own focal then link all the focals?

Are there any concerns in doing so?
Environment:
SOLVE:Operations all releases
Netmaster Suite All releases
Answer:
Theoretically there is no limit to the number of regions that can be linked and synced.
An unstated 'best practices' limit is 12 subordinates to one focal, but there's no real limit s long as  enough memory , and sufficient space for the RAMDB is allocated to hold all the necessary information from the many regions.

If  different groups are linked together with one focal each, then the focals linked together, the cumulative content of the focal RAMDBs will be copied to all RAMDBs.
All of that is entirely possible.

Where  problems occur is if one region hits a problem (abend or other problem on that LPAR) or something goes haywire in the network.
The linking for that region may need to be repaired in multiple locations.

When applying maintenance,  be careful about interactions between regions of varying maintenance levels; possibly unlinking, upgrading, then re-doing the link and sync.

When upgrading to 12.2 this can also cause issues if not handled correctly. The link and sync process is generally backward compatible but not forward compatible, so 12.2 regions may see 12.1 data, but 12.1 regions will not see 12.2 data. Regions being upgraded need to be properly unlinked prior to the upgrade to avoid problems, especially if some back and forth is needed between releases a couple times during initial testing.

The few customers with large numbers of regions linked and synced had problems frequently enough that they ended up either scaling back the number of regions linked together, or using normal linking without the syncing up.