Technical data

Managing User Accounts
7.1 Understanding the User Authorization File
7.1 Understanding the User Authorization File
The system user authorization file (UAF), SYS$SYSTEM:SYSUAF.DAT, contains
user account records. Each record consists of fields that provide information
about the account’s user name, login characteristics, login restrictions, and
resource control attributes. You specify the account user name as a parameter
to AUTHORIZE commands; the other fields are specified as qualifiers to
AUTHORIZE commands.
The system uses the UAF to validate login requests and to set up processes for
users who successfully log in. You create, examine, and modify UAF records with
the Authorize utility (AUTHORIZE).
You can assign the following resource control attributes in the UAF record:
• Priority
• Limits and quotas
• Privileges
The following sections briefly discuss these resource control attributes.
7.1.1 Priority
A user’s priority is the base process priority that the system uses to schedule
computer time for the process associated with the user’s account.
On VAX systems, priorities range in value from a low of 0 to a high of 31. 0
through 15 are timesharing priorities; 16 through 31 are real-time priorities.
On Alpha systems, priorities range in value from a low of 0 to a high of 63. 0
through 15 are timesharing priorities; 16 through 63 are real-time priorities.
The system schedules processes with real-time priorities strictly according to base
priority—the executable real-time process with the highest base priority executes
first. Processes with timesharing priorities are scheduled according to a slightly
different principle, to promote equitable service to all users.
Leave the base priority at the default of 4 for timesharing accounts.
7.1.2 Limits and Quotas
Limits are set on system resources that can be reused; for example, the amount
of memory that a process can use for I/O requests. Most limits restrict the use of
physical memory. You set limits for processes associated with accounts through
the appropriate UAF fields. You can change some of these limits later with DCL
commands or by calling system services from programs.
A process passes on its resources to a subprocess (for example, when you create a
subprocess with the SPAWN command) in one of several ways, depending on the
resource type. Table 7–1 lists the different resource types.
7–2 Managing User Accounts