The Solaris Resource Manager management model organizes lnodes into a hierarchical structure called the scheduling tree. The scheduling tree is organized by UID: each lnode references the UID of the lnode's parent in the tree.
Each sub-tree of the scheduling tree is called a scheduling group, and the user at the root of a scheduling group is the group header. (The root user is the group header of the entire scheduling tree.) Setting the flag flag.admin delegates the ability to manage resource policies within the scheduling group to the group header.
Lnodes are initially created by parsing the UID file. After Solaris Resource Manager has been installed, the lnode administration command (limadm(1MSRM)) is used to create additional lnodes and assign them to parents. The scheduling tree data is stored in a flat file database that can be modified as required using limadm.
Although a UID used by an lnode does not have to correspond to a system account, with an entry in the system password map, it is recommended that a system account be created for the UID of every lnode. In the case of a non-leaf lnode (one with subordinate lnodes below it in the hierarchy), it is possible for the account associated with the lnode to be purely administrative; no one ever logs in to it. However, it is equally possible that it is the lnode of a real user who does log in and run processes attached to this non-leaf lnode.
Note that Solaris Resource Manager scheduling groups and group headers have nothing to do with the system groups defined in the /etc/group database. Each lnode in the scheduling tree, including group headers, corresponds to a real system user with a unique UID.
If a hierarchical limit is assigned to a group header, it applies to the usage of that user plus the total usage of all members of the scheduling group. This allows limits to be placed on entire groups, as well as on individual members. Resources are allocated to the group header, who can allocate them to users or groups of users that belong to the same group.