You can use CPU DR to decrease the number of the control domain's cores from an initial factory-default configuration. However, you must use a delayed reconfiguration instead of a memory DR to decrease the control domain's memory.
When in the factory-default configuration, the control domain owns all of the host system's memory. The memory DR feature is not well suited for this purpose because an active domain is not guaranteed to add or, more typically, give up, all of the requested memory. Rather, the OS running in that domain makes a best effort to fulfill the request. In addition, memory removal can be a long-running operation. These issues are amplified when large memory operations are involved, as is the case for the initial decrease of the control domain's memory.
Note - When the Oracle Solaris OS is installed on a ZFS file system, it automatically sizes and creates swap and dump areas as ZFS volumes in the ZFS root pool based on the amount of physical memory that is present. If you change the domain's memory allocation, it might alter the recommended size of these volumes. The allocations might be larger than needed after reducing control domain memory. For swap space recommendations, see Planning for Swap Space in Managing File Systems in Oracle Solaris 11.3. Before you free disk space, you can optionally change the swap and dump space. See Managing ZFS Swap and Dump Devices in Managing ZFS File Systems in Oracle Solaris 11.3.
This procedure shows how to decrease the CPU and memory resources from the control domain's initial factory-default configuration. You first use CPU DR to decrease the number of cores and then initiate a delayed reconfiguration before you decrease the amount of memory.
The example values are for CPU and memory sizes for a small control domain that has enough resources to run the ldmd daemon and to perform migrations. However, if you want to use the control domain for additional purposes, you can assign a larger number of cores and more memory to the control domain as needed.
See How to Configure the Control Domain.