Restrictions on ECS Mode Usage

There are several restrictions on using ECS mode:

ECS and VVDS protocols cannot be used simultaneously for a catalog. This is enforced by the catalog address space. If you attempt to use a catalog that is currently ECS-active from a non-ECS system in the sysplex, the associated catalog request fails with return code RC228 and reason code RSN26.
Warning: Access to ECS catalogs is restricted to within a parallel sysplex. Attempts to alter ECS-active catalogs from outside the sysplex result in data integrity errors. If you must access a catalog that is or has been ECS-active in a sysplex from outside the sysplex, you must first explicitly deactivate the catalog by issuing the following operator command from one of the systems within the sysplex:
```
MODIFY CATALOG,ECSHR(REMOVE,catname)
```
If you must access multiple or an unknown number of ECS-eligible catalogs outside the sysplex, follow the procedure described in Disconnecting from the structure to disconnect all systems in the sysplex from the structure. Taking a system down or out of the sysplex does NOT properly deactivate ECS-active catalogs.
No more than 1024 catalogs can currently be shared using ECS from a single system.
All systems sharing the catalog in ECS mode must have connectivity to the same Coupling Facility, and must be in the same global resource serialization (GRS) complex.
When you use catalogs in ECS mode, convert the resource SYSIGGV2 to a SYSTEMS enqueue. Otherwise, the catalogs in ECS mode will be damaged.