Preventing New System Activity

You control the number of executing jobs and sessions with two commands, LIMIT and JOBFENCE. The LIMIT command controls the number of jobs or sessions that execute concurrently. (The limits you set with the LIMIT command cannot exceed the maximum job/session limit determined by your system configuration.)

The JOBFENCE command lets you choose the priority jobfence--a number between 0 and 14 (inclusive). Each session and job logs on to the system with an input priority between 1 and 13 (inclusive); the default input priority for standard MPE users is 8. In order for a session or job to execute, its input priority must exceed the current jobfence.

When you set the jobfence high, jobs with an input priority less than or equal to the jobfence enter the WAIT state. MPE XL refuses attempts to initiate a session with an input priority that does not exceed the current job fence. Users see the following message:

   CAN'T INITIATE NEW SESSIONS NOW.

If you set the jobfence to its highest possible value, 14, only users assigned system manager (SM) or system supervisor (OP) capability are able to log on. (System managers and system supervisors are the only users allowed to log on with the HIPRI parameter of the HELLO and JOB commands.) Setting the jobfence to 14 prevents all other users from gaining access to the system during a system backup. Enter:

   :LIMIT 0,0
   :JOBFENCE 14

To check the new job/sessions limits and the system jobfence, enter:

   :SHOWJOB STATUS

The last line of the message on your console should now exactly match the example shown below:

   JOBFENCE= 14; JLIMIT= 0; SLIMIT= 0

If you see anything else, you made a mistake entering the LIMIT and JOBFENCE commands. Follow the instructions again.

	NOTE: For an online backup, make sure that no one logs onto the system while the backup is starting. Once TurboSTORE informs you that files can be modified, via a console message, you can allow users to log on again. For a 7x24 true-online backup, you do not have to prevent new system activity. All normal system activity can continue during the backup. Even though jobs and sessions can continue to run during both an online and 7x24 true-online backup, it is not advised that you run processor or disk intensive jobs during a backup. Doing so will degrade both the backup's and the job's performance. If possible, try to schedule large jobs and backups at different times.