Using the Realtime Monitor › Database Overview (PF11)

Database Overview (PF11)

 PM-Rnn.n SYSTEM71         CA, Inc.                  V71      08.348 14:53:56.39
 CMD-->                                                             Window : 02
                                                                    Refresh: 10
   02 Database Overview
       _ Database Record Summary
 Requested   Current    Fragmented
 5691738     1303479    405
    Overflow            On Target
 Calc     Via        Calc     Via
 48       6758       1349     21782
 DB Calls    DB Req     Relocated
 3397293     3850790    0

  _ Database Page I/O Summary
  Pages Read Written    Requested
  563146     49946      5364718

Screen Description

The Database Overview screen displays summary information about database access. The screen is divided into two parts:

• Record access activity
• Page I/O activity

To view detailed information about active transactions and buffer use, you can request the Transaction Detail and Buffer I/O Summary screens directly from the Database Overview screen:

• To request the Transaction Detail screen, type any nonblank character in the select field to the left of the Database Record Summary field.
• To request the Buffer I/O Summary screen, type any nonblank character in the select field to the left of the Database Page I/O Summary field.

When you have selected one or both screens, press [Enter]. The Realtime Monitor creates a new window for each screen requested.

What To Look For

• Look for a high number of stored record fragments, which can indicate that:
  • Many database pages are full
  • Size specifications for variable-length records are inefficient

  Use the IDMSDBAN utility to analyze the space available in the database. As necessary, increase the database page size or the number of pages in the database, or change variable-length record-size specifications using the MINIMUM ROOT and MINIMUM FRAGMENT parameters of the schema compiler RECORD statement.

• Look at the ratio of CALC records stored on target pages relative to the sum of these records plus overflow CALC records. The ratio, which indicates how well the CALC algorithm works, should be 1. A ratio less than 1 indicates that space utilization is high. Use the Interval Monitor to track this ratio over time. Use the IDMSDBAN utility to analyze space utilization in the database.
• Look at the ratio of VIA records stored on target pages relative to the sum of these records plus overflow VIA records. The ratio, which indicates how well VIA records cluster around their owner, should be 1. A ratio less than 1 indicates one of these conditions exist:
  • Large data clusters
  • High space utilization
  • Small page sizes

  Use the Interval Monitor to track this ratio over time. Use the IDMSDBAN utility to analyze space utilization in the database.

• Look at the ratio of database pages requested to pages read. The ratio indicates how well the buffer is sized and how well the database is designed. Low ratios could indicate that the buffer is too small or that database I/O needs to be tuned.