PRM Product Overview

11
Allocating resources to users
With HP Process Resource Manager, you can easily manage resource allocations to users, as well as
applications, by assigning users to PRM groups.
After defining PRM groups and setting resource allocations for CPU, real memory, and disk I/O
bandwidth resources, you can specify how users are assigned to the PRM groups. This feature is
useful for systems in which users are logging on and accessing interactive applications. PRM enables
you to specify, for each valid user name, which PRM group the user is assigned to when logging on
to the system. Then, when users access the system, their UNIX shell processes are automatically
placed in their assigned PRM groups. Because a child process inherits the parent process’s PRM
group affiliation, all applications and jobs run by a user also execute in the assigned PRM group. All
users and applications in a PRM group share the resources assigned to that PRM group. If a user does
not have an assigned PRM group, the user’s shell process is placed in the default PRM group OTHERS
at login and that user is not allowed to access other PRM groups.
PRM configuration allows netgroups in user records to specify initial and alternate PRM groups for all
members of a netgroup*. Instead of adding a user record for each user on the system, you could
create only one user record. This record would be for a netgroup you define, for example,
finance_dept. The netgroup would include these users. Using a netgroup also simplifies updates when
the staff changes.
Similarly, PRM enables you to place processes based on their effective UNIX group IDs, as described
in the “Allocating resources to UNIX groups” section.
The PRM user assignment feature is integrated with standard HP-UX commands such as cron and at.
This integration ensures that commands—or jobs that are executed on behalf of users at specified
times—run in the appropriate PRM groups as well.
Assigning users to PRM groups ensures user processes receive the assigned allocations for CPU, real
memory, and disk I/O bandwidth resources when the system is under heavy load. When using pSet
PRM groups or when using FSS PRM groups with CPU capping enabled, users are prevented from
using more than their CPU allocation, which ensures they always see a consistent level of system
responsiveness. The objective with this PRM feature is not to restrict users’ connect time as might be
the case with a campus student server—there are already tools to deal with that problem. The
objective is to ensure a consistent level of service to users of servers in an enterprise.
Allocating resources to UNIX groups
UNIX groups defined in /etc/group enable you to easily give a collection of users the same level of
access to various files on a system. You can configure PRM to provide a UNIX group with a certain
level of access to system resources as well, placing processes in PRM groups based on their effective
UNIX group IDs.
* The file /etc/netgroup defines network-wide groups and is used for permission checking when executing remote mounts, remote
logins, and remote shells. For remote mounts, the information in netgroup classifies machines. For remote logins and remote shells, it
classifies users. See the netgroup(4) man page for additional details.