Check mode

Before IOPT is activated using IOPT_SET_ON=YES, IOPT means can be used to check whether it makes sense to use IOPT.

The following requirements apply for check mode:

• IOPT must be activated using the CHK option (IOPT_SET_ON=CHK, see "Activating and deactivating IOPT").

• I/O priority classes must be defined for tasks (/MODIFY-TASK-CATEGORIES or IOPT statement IOPT_PRI (see "Defining and querying threshold values for I/O priority classes")).

• The threshold values for the utilization by tasks with the various priority classes must be defined (see IOPT statements IOPT_LOW_... and IOPT_MED_...).

The IOPT_CHK_RESET statement defines the time at which the check should begin. You can subsequently (for example an hour or day later) use IOPT_CHK_...? statements to query how often IOPT has locked low-priority tasks.

The check period taken into account always begins with the IOPT_CHK_RESET statement and ends at the time a query is made.

Starting the check

IOPT_CHK_RESET                                                                                                                                  

IOPT_CHK_RESET

Querying the locks for channels

IOPT_CHK_CHN?                                                                                                                                     

IOPT_CHK_CHN?mask

mask	Specifies a channel. The following specifications are possible:
	*	The locks for all channels is listed.
	nm	The locks for channel nm are listed.

Querying the locks for paths

IOPT_CHK_PTH?                                                                                                                                     

IOPT_CHK_PTH?mask

mask	Specifies a path. The following specifications are possible:
	*	The locks for all paths are listed.
	nmlo/pq	The lock for the path from channel pq to controller nmlo is listed.

Querying the locks for ports

IOPT_CHK_POR?                                                                                                                                   

IOPT_CHK_POR?mask

mask	Specifies a port. The following specifications are possible:
	*	The locks for all ports are listed.
	portname	The locks for the port with the specified name are listed.

Querying the locks for devices

IOPT_CHK_DEV?                                                                                                                                    

IOPT_CHK_DEV?mask

mask	Complete or masked specification of a mnemonic device name. The following specifications are possible:
	*	The locks for all devices are listed.
	n*	The locks for all devices whose names begin with n are listed.
	nm*	The locks for all devices whose names begin with nm are listed.
	nml*	The locks for all devices whose names begin with nml are listed.
	nmlo	The lock for the device with the name nmlo is listed.

Example

I/Os are active for the devices 3801 and 3803 on the 3800 controller and on channel 50. The FC port connected to the controller has the WWPN 5006048448586C01.

Query for channels

IOPT_CHK_CHN?*

Output:

    UNIT NAME    | FREQUENCY % 
-----------------+-------------
50               |      73

73 % of the lock conditions for channel 50 were satisfied.

Additional quantitative analysis for channel 50:

IOPT_INF_CHN?50

Output:

    UNIT NAME     | HIG MED LOW | EXPLICIT DELAY | IMPLICIT DELAY 
                  |  %   %   %  |   MED     LOW  |   MED     LOW
------------------+-------------+----------------+---------------
50                |  22  22  44 |    0       0   |    0       0

Query for paths

IOPT_CHK_PTH?*

Output:

    UNIT NAME    | FREQUENCY % 
-----------------+-------------
3800/50          |      73   

73 % of the lock conditions for path 3800/50 (controller/channel) were satisfied.

Additional quantitative analysis for path 3800/50:

IOPT_INF_PTH?3800/50

Output:

    UNIT NAME     | HIG MED LOW | EXPLICIT DELAY | IMPLICIT DELAY 
                  |  %   %   %  |   MED     LOW  |   MED     LOW
------------------+-------------+----------------+--------------
3800/50           |  22  22  44 |    0       0   |    0       0

Query for ports

IOPT_CHK_POR?*

Output:

    UNIT NAME    | FREQUENCY % 
-----------------+-------------
5006048448586C01 |      73

73 % of the lock conditions for port 5006048448586C01 were satisfied.

Additional quantitative analysis for port 5006048448586C01:

IOPT_INF_POR?5006048448586C01

Output:

    UNIT NAME     | HIG MED LOW | EXPLICIT DELAY | IMPLICIT DELAY 
                  |  %   %   %  |   MED     LOW  |   MED     LOW
------------------+-------------+----------------+---------------
5006048448586C01  |  22  22  44 |    0       0   |    0       0

 

Query for devices

IOPT_CHK_DEV?*

Output:

    UNIT NAME    | FREQUENCY % 
-----------------+-------------
3801             |      73 
3803             |      73 

73 % of the lock conditions for devices 3801 and 3803 were satisfied.

Additional quantitative analysis for devices 3801 and 3803:

IOPT_INF_DEV?380*

Output:

    UNIT NAME     | HIG MED LOW | EXPLICIT DELAY | IMPLICIT DELAY 
                  |  %   %   %  |   MED     LOW  |   MED     LOW
------------------+-------------+----------------+---------------
 3800             |  0   0   0  |    0       0   |    0       0
 3801             |  48  0   48 |    0       0   |    0       0
 3802             |  0   0   0  |    0       0   |    0       0
 3803             |  0   48  48 |    0       0   |    0       0

With this utilization it makes sense to have the I/Os for devices 3801 and 3803 controlled by IOPT.