IORM Dynamic control of I/O resources

Version:	IORM V21.0C
Privileges:	TSOS or OPERATING

The IORM utility routine is started using /START-IORM (TSOS or OPERATING privilege).

The IORM (I/O Resource Management) utility routine enhances the I/O properties of BS2000 in native and VM2000 modes.

The following functions are implemented in IORM for the autonomous, dynamic control of the I/O resources channel, controller, path and device:

• IOPT: I/O Priority Handling for Tasks

• DDAL: Optimized Dynamic Device Allocation in ETERNUS CS operation

• IOLVM (/390 server): I/O Limit for certain Virtual Machines

IORM also offers the following function:

• DPAV (/390-Server) Settings for PAV and FastDPAV:
  No longer supported for use as dynamic I/O load balancing for disks (Dynamic Parallel Access Volume), but exclusively for monitoring utilisation and limiting the number of FastDPAV alias devices for individual disks.

During ongoing operation, IORM collects data on the utilization of the I/O resources and controls I/O operation in accordance with specified threshold values.

The IORM functions IOPT and IOLVM control disk devices.
The IORM function DDAL controls tape devices, see "IORM Dynamic control of I/O resources".

When IORM is used in the monitor system and in the BS2000 guest systems involved in VM2000 mode, the IORM subsystems exchange I/O data and control information via an internal interface.

IORM can be used in native mode and under VM2000 on all BS2000 servers. IORM works on a cross-VM but not on a cross-server basis.

Installation of IORM

IORM is installed using the IMON installation monitor.

SYSLNK.IORM.<version>	Module library for /390 servers
SKMLNK.IORM.<version>	Module library for x86 servers
SYSMES.IORM.<version>	Message file
SYSSDF.IORM.<version>	SDF syntax file
SYSSSC.IORM.<version>	Subsystem catalog
SYSDAT.IORM.<version>	Parameter file
SYSSII.IORM.<version>	Structure information
SYSNRF.IORM.<version>	NOREF file
SYSRMS.IORM.<version>	RMS delivery packet
SYSRME.IORM.<version>.D/E	Readme file (German/English)
SYSFGM.IORM.<version>.D/E	Release Notice (German/English)

Table 2: Delivery components of IORM

Parameter file of IORM

In the parameter file $<user ID>.SYSDAT.IORM.<version> you can enter specifications for IORM which are processed the first time IORM is started. The parameter file consists of comment lines and value lines with statements for IORM. When supplied, the parameter file contains comment lines with sample statements for IORM.

IORM subsystem

Before the IORM utility routine is started for the first time, the IORM subsystem must be loaded using:

/START-SUBSYSTEM SUBSYSTEM-NAME=IORM

The subsystem IORM is terminated using:

/STOP-SUBSYSTEM SUBSYSTEM-NAME=IORM

If, at this time, the IORM utility routine is still in use, the subsystem remains in the IN DELETE / WAIT-DISCON state until usage comes to an end.

Starting the IORM utility routine

The IORM utility routine is started using /START-IORM (TSOS or OPERATING privilege).

START-IORM                                                        Alias: IORM

VERSION = *STD / <product-version>

,MONJV = *NONE / <filename 1..54 without-gen-vers>

,CPU-LIMIT = *JOB-REST / <integer 1..32767 seconds>

The first time the IORM utility routine is started, the actions required for IORM operation are executed under the user ID where /START-IORM has been entered: configuring tables, connecting to the BS2000 I/O system, processing the statements from the IORM parameter file. IORM then terminates.
In VM2000 mode, IORM should be started in all BS2000 guest systems.

When IORM is started again, you can enter statements for IORM via SYSDTA. These statements control the execution of IORM. The statements can be entered directly in a dialog or in file form.

 

Example

/START-SUBSYSTEM SUBSYSTEM-NAME=IORM                                      1.
ESM0216 FUNCTION 'CREATE' STARTED FOR SUBSYSTEM 'IORM    /<version>' 
/...
/start-iorm                                                               2.
BLS0523 ELEMENT 'IORM-TU', VERSION '<version>', TYPE 'L' FROM LIBRARY 
        ':SBZ7:$TSOS.SYSLNK.IORM.<version>' IN PROCESS 
BLS0524 LLM 'IORM-TU', VERSION '<version>' OF '<date> <time>' LOADED 
/start-iorm                                                               3.
BLS0523 ELEMENT 'IORM-TU', VERSION '<version>', TYPE 'L' FROM LIBRARY 
        ':SBZ7:$TSOS.SYSLNK.IORM.<version>' IN PROCESS 
BLS0524 LLM 'IORM-TU', VERSION '<version>' OF '<date> <time>' LOADED 
* iopt_set_on? 
IOPT_SET_ON=NO                                                             4.
* ...
//END
/...
/ASSIGN-SYSDTA TO=SYSDAT.IORM.NIGHT                                        5.
/START-IORM 
BLS0523 ELEMENT 'IORM-TU', VERSION '<version>', TYPE 'L' FROM LIBRARY 
        ':SBZ7:$TSOS.SYSLNK.IORM.<version>' IN PROCESS 
BLS0524 LLM 'IORM-TU', VERSION '<version>' OF '<date> <time>' LOADED 
/...
/ASSIGN-SYSDTA TO=SYSDAT.IORM.DAY                                          6.
/START-IORM 
BLS0523 ELEMENT 'IORM-TU', VERSION '<version>', TYPE 'L' FROM LIBRARY 
        ':SBZ7:$TSOS.SYSLNK.IORM.<version>' IN PROCESS 
BLS0524 LLM 'IORM-TU', VERSION '<version>' OF '<date> <time>' LOADED 
/...

1. The IORM subsystem is started.

2. The IORM utility routine is started for the first time for initialization purposes.

3. The IORM utility routine is started again to enter statements.

4. The specifications in the parameter file apply.

5. During the night, the IORM subsystem that is already active obtains new specifications from the SYSDAT.IORM.NIGHT file.

6. The next morning, the IORM subsystem that is still active obtains new specifications from the SYSDAT.IORM.DAY file.

IORM statements

IORM statements consist of character and numeric strings without blanks.Comment lines begin with *.

IORM knows the following general statements:

END	Terminates the IORM utility routine. The IORM subsystem and its functions remain active.
HELP	Displays the IORM statements.

IORM_DUMP  Creates IORM diagnostic documentation.

The other statements are function-specific and are described together with the function concerned.

Hardware dependencies of IORM

IORM supports the following hardware components:

IORM function	Hardware supported
IOPT	Disks on all BS2000 servers
DPAV	Disks connected to the Fibre Channel of /390 servers DPAV is not available on the Fibre Channel of x86 servers. IO parallelism is supported here for emulated disks (RSC).
DDAL	Tape devices on all BS2000 servers
IOLVM	Disks on all BS2000 servers

Behavior in the event of an error, creation of diagnostic documentation

To permit IORM problems to be diagnosed and rectified, it is necessary that sufficient error documents should be created and stored at the earliest possible time. In the case of reproducible errors, a precise description should be provided of how an error can be generated.

In addition to the CONSLOG file and the IORM statements, a file with the IORM dump should always be created using the following statement sequence:

/ASSIGN-SYSLST TO=<file>
/START-IORM 
* IORM_DUMP
* END 
/ASSIGN-SYSLST TO=*PRIMARY

In the event of problems with DPAV or DDAL in VM2000 mode, these documents are also required from the monitor system and the guest systems involved.