2. PERFORMANCE REPORTING ANALYSIS › 2.3 Auxiliary Storage Management Analysis

2.3 Auxiliary Storage Management Analysis

Virtual systems must maintain a copy of all virtual memory
pages.  In MVS, this function is carried out by the Auxiliary
Storage Manager (ASM).  This chapter describes the structure
and operation of ASM.  Auxiliary storage is defined as
several direct access data sets, each of which provides
storage capacity for one of two major areas:

    o  Paging space
    o  Swapping space

In MVS, ASM supports three logically distinct groups of
pages:  pages from the pageable link pack area, pages from
the common system area, and pages from the private area.  At
least one page data set must be defined for each group of
pages.

There is a single page data set to hold pages from the
pageable link pack area (the PLPA data set), one to hold
common system area pages (the common data set), and one or
more to hold pages from the private area (the local data
sets).  Organizing auxiliary storage in this manner allows
I/O overhead to be spread across several data sets and
permits concurrent processing of many virtual pages.

This chapter describes the use of these page and swap data
sets by ASM, including the paging control algorithms, data
set selection algorithms, and the swapping process.  ASM
operation is described through MVS/SP 2.1.2 (MVS/XA).  Data
set configurations and device selection considerations in
using drums and 3330, 3350, and 3380 devices are discussed.

The reports produced by the CA MICS Auxiliary Storage
Management Analysis inquiries give you the capability to
monitor the operation of ASM in terms of utilization and
response by:

    o  Individual page or swap data sets.

    o  Page space type (e.g., the local data sets).

    o  Device type (to compare the service provided by 3380s
       to that provided by 3350s, for example).

You can produce these reports from the CA MICS RMF product
data at any supported timespan and summarization level using
the SCPPSDnn and HARDVAnn Files.  The availability of each
summary option depends on the generation of the SCPPSD Files
at the corresponding level of summarization.  The CA MICS
default is to produce files at the DETAIL, DAYS, and WEEKS
levels, but not at the MONTHS level.

The response time reports indicate problems that result from
the impact of paging I/O on the I/O subsystem or the impact
of the I/O configuration on the page/swap data sets.  You can
use the reports described in Section 2.4, I/O Configuration
Analysis, to examine these problems.

The following sections describe the operation of the
Auxiliary Storage Management Analysis inquiries and how to
use the reports that are produced:

    1 - Functional Description
    2 - Usage Guidelines
    3 - Standard Output
    4 - MVS Concepts
    5 - Case Study
    6 - Component Operation
    7 - Requirements