Siemens SM2 monitoring system User Manual

U3585-J-Z125-8-76

39

SM2 monitoring programs

COSMOS is an event-driven monitoring program for recording detailed system data that is
required particularly for bottleneck analyses of OLTP applications. It collects monitored data
for all tasks, for task groups (which can be selected by user ID, category, or job name), or
for individual tasks. Because of the high volume of very detailed monitored data involved,
COSMOS should only be used for short-term monitoring. Intimate knowledge of the internal
workings of the system is required to interpret the monitored data.

COSMOS is an SM2 add-on product and only available on special release. A detailed
description is supplied with the product.

SM2 outputs highly detailed information on DAB activity in all DAB cache areas. Intensive
use of DAB in parallel may result in a large volume of data traffic in SM2.

The monitoring program for disk statistics permits fine analysis of the frequency with which
the cylinders or blocks of a disk are accessed, and of the duration of I/O operations. SM2R1
provides analyses of the records supplied by SM2. These analyses, combined with a
knowledge of how files are mapped to cylinder/block areas, make it possible to optimize the
mean access time for disk I/O operations.

The following information is recorded for each completed disk access to a selected disk
device:

–

mnemonic device name

–

cylinder/block number addressed when I/O is started (at the time of the SDV or START-
SUBCHANNEL command)

–

duration of hardware I/O (time between the initiation of I/O using the SDV or START-
SUBCHANNEL command) until termination of I/O (as the result of a channel interrupt)

–

I/O identifier specifying read, write or other I/O operations

The monitored data recorded is then written only to an SM2 output file, from which it can be
analyzed by SM2R1 (PRINT-DISK-STATISTICS statement).