Fujitsu BS2OSD Manuale Utente

 

Page 18

 

 

2.16.1  Autonomous, dynamic control of I/O resources (IORM) 
 

  *4 

The new utility program IORM facilitates autonomous, dynamic  

  *4 

control of the I/O resources, devices, controllers, channels  

  *4 

(type S and type FC) and paths. Both S and SX servers are  

  *4 

supported in native and in VM2000 operation. 

  

  *4 

The following functions are implemented:  

  

  *4 

- IOPT:  I/O priority control for tasks with competing access  

  *4 

 

 

to one device (I/O Priority Handling for Tasks)  

  *4 

- DPAV:  Dynamic I/O load distribution for S server disks  

  *4 

    

on the FC channel (Dynamic Parallel Access Volume)  

  *4  

- DDAL 

Optimized load distribution in CentricStor operation  

  *4  

 

 

(Dynamic Device Allocation)  

  *4 

- IOLVM:  Limiting of I/O throughput for single VM2000 guest  

  *4 

systems (I/O-Limit for Virtual Machines)  

  *4 

- TCOM:  Adapting the compression for LTO devices  

  *4 

(Tape Compression)  

  

  *4 

The IOPT, DPAV and IOLVM functions control disks, the DDAL and 

  *4 

the TCOM functions control tape devices.  

  *4 

IORM links itself into the BS2000 I/O system and collects I/O  

  *4 

data to determine the I/O resources utilization. IORM also  

  *4 

periodically checks whether intervention in the I/O operation  

  *4 

is required.  

  *4 

The values set for intervention such as thresholds, selection of  

  *4 

devices to be monitored or I/O priorities can be passed to IORM  

  *4 

in the form of a parameter file or in dialog.  

  *4 

IORM has a HELP function that outputs all permitted statements  

  *4 

together with their syntax. 

  *4 

You will find a detailed description in the SYSRME.IORM.060.E  

  *4 

file or in the utilities manual.  

 

  *4 

I/O-Priority control for tasks (IOPT) 

 

  *4 

I/O-intensive but relatively unimportant applications can  

  *4 

obstruct other, more important applications if the I/Os are on  

  *4 

the same device or on devices on the same controller, path,  

  *4 

port or channel.  

  *4 

Three I/O priorities, low, medium and high, were therefore  

  *4 

introduced for IORM. 

  *4 

If the IOPT function is activated in IORM (IOPT_SET_ON=YES  

  *4 

statement), IORM applies brakes to the tasks with low and medium  

  *4 

priorities by assigning time penalties if these tasks hinder  

  *4 

tasks with higher priorities. 

  *4 

IORM does not affect tasks with I/O priority high. 

  *4 

I/Os via FDDRL, ARCHIVE, VOLIN or PAGING are also not braked.