Using the Interval Monitor › Buffer Detail (PF9)

Buffer Detail (PF9)

 PM-Rnn.n SYSTEM71         CA, Inc.                  V71      08.348 11:14:06.96
 CMD-->                                                             Window : 02

   02 10:30 BUDT Buffer Detail                                                >
   Buffer Name         Buffer     Pages Found_In    % Buffer Prefetch   Pages
                        Waits Requested   Buffer Utilization     Hits    Read
   DBCR_BRCH_BUFFER         0        0         0       0            0       0
   DBCR_ACCT_BUFFER         0        0         0       0            0       0
   LOG_BUFFER               0        0         0       0            0       0
   DEFAULT_BUFFER           0        4         0       0            0       4

 PM-Rnn.n SYSTEM71         CA, Inc.                  V71      08.348 11:14:06.96
 CMD-->                                                             Window : 02

   02 10:30 BUDT Buffer Detail                                             <  >
   Buffer Name          Pages Found-In   Pages  Buffer   Pages Pages  Buffer
                         Read    Cache Written    Size Defined  Used   Flush
   DBCR_BRCH_BUFFER         0        0       0    4000    500    200       0
   DBCR_ACCT_BUFFER         0        0       0    2932    500    200       0
   LOG_BUFFER               0        0       0    4276      5      0       0
   DEFAULT_BUFFER           4        0       0    4276     60     30       0

 PM-Rnn.n SYSTEM71         CA, Inc.                  V71      08.348 11:14:06.96
 CMD-->                                                             Window : 02

   02 10:30 BUDT Buffer Detail                                             <  >
 Buffer Name         Buffer  Buffer SHR_Buffer SHR_Buffer EXC_Buffer EXC_Buffer
                      Flush    Time      Waits       Time      Waits       Time
 DBCR_BRCH_BUFFER         0  .0000S         0     .0000S          0     .0000S
 DBCR_ACCT_BUFFER         0  .0000S         0     .0000S          0     .0000S
 LOG_BUFFER               0  .0000S         0     .0000S          0     .0000S
 DEFAULT_BUFFER           0  .0000S         0     .0000S          0     .0000S

 PM-Rnn.n SYSTEM71         CA, Inc.                  V71      08.348 11:14:06.96
 CMD-->                                                             Window : 02

   02 10:30 BUDT Buffer Detail                                             <
   Buffer Name        EXC_Buffer EXC_Buffer DB_Read DB_Read DB_Write DB_Write
                           Waits       Time   Waits    Time    Waits     Time
   DBCR_BRCH_BUFFER           0     .0000S        0  .0000S        0   .0000S
   DBCR_ACCT_BUFFER           0     .0000S        0  .0000S        0   .0000S
   LOG_BUFFER                 0     .0000S        0  .0000S        0   .0000S
   DEFAULT_BUFFER             0     .0000S        4  .0794S        0   .0000S

Screen Description

The Buffer Detail screen displays statistics related to database and journal buffer use for the current interval. The screen includes one line for each buffer defined to the DC/UCF system and shows a breakdown of statistics describing the efficiency of buffer use.

Using This Screen

To request the Buffer History screen, press [PF9].

What To Look For

• Look at the ratio of Pages Read to Pages Requested. This ratio measures the effectiveness of the buffer pool size and design of the database. If the ratio is consistently low, this may indicate that the size of the buffer is too small or the database needs to be tuned. If the ratio is low, you can change the DMCL to:
  • Increase the number of pages in the buffer
  • Change the buffer and area assignments

  If the interval includes transactions that keep locks, this ratio may be artificially high because of the nature of the internal locking mechanism. IDMSDBMS cannot hold a buffer while requesting a lock. Therefore, when locks are kept, IDMSDBMS must free and request a page each time a record is requested.

  Note: By increasing the amount of buffer space, you decrease the amount of storage available for the DC/UCF system and you can cause paging. If space is tight, allocate the space elsewhere; for example, a program pool. If paging increases, decrease the size of the buffer.

• Look for buffer wait counts greater than zero and try to determine the cause.