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How to decrease Buffers Flushed?


Article Number000020802
EnvironmentProduct: Progress OpenEdge
Version: All supported versions
OS: All supported platforms
Question/Problem Description
How to decrease Buffers Flushed (PROMON Activity or _ActBuffer._Buffer-Flushed VST)?
When should I use more APWs?
Steps to Reproduce
Clarifying Information
PROMON > 5.  Activity

Event                 Total   Per Sec   Event                 Total   Per Sec
       Commits    1,871,989        13          Undos          1,128         0
Record Updates    1,970,778        14   Record Reads    551,394,617     3,893
Record Creates    2,818,960        20 Record Deletes      4,495,568        32
     DB Writes    1,871,872        13       DB Reads    194,533,556     1,373
     BI Writes      775,827         6       BI Reads         73,278         1
     AI Writes      532,784         4
  Record Locks   45,121,528       319   Record Waits           2116         1
   Checkpoints          122         0  Buffs Flushed         59,181        23

Rec Lock Waits      0   BI Buf Waits      0 %    AI Buf Waits      0 %
Writes by APW       1   Writes by BIW     1 %    Writes by AIW     1 %
Buffer Hits         1   Primary Hits     74 %    Alternate Hits    0 %
DB Size        878 GB        BI Size  1023 MB        AI Size     128 K
FR chain              1739223 blocks  RM chain        77672987  blocks
Shared Memory  7392M        Segments      1

1 Servers, 125 Users,1 Apws

Buffers Flushed metrics are found in several PROMON views:
  • promon -> 5. Activity    "Buffs Flushed"
  • promon -> R&D -> 2. Activity Displays -> 1. Summary       "Flushed at chkpt"
  • promon -> R&D -> 2. Activity Displays -> 4. Page Writers  "Flushed at checkpoint"
  • promon -> R&D -> 3. Other Displays   -> 4. Checkpoints.  (per individual checkpont)
Error Message
Defect/Enhancement Number
With an Enterprise database license, start an additional APW. 
As general rule of thumb, if the number of buffers flushed is higher than 10, increase the bicluster size, increase the number of page writers, or increase disk write capacity. For further advice refer to Article: With a Workgroup or Personal database license, since APWs are not available increasing the BI Cluster size would likely increase the duration of the checkpoints further as the first process that needed to move to a new BI cluster would first have to write all database buffers that were referenced in the BI cluster. Consider upgrading to an Enterprise Database License if performance is a priority.
Last Modified Date8/27/2019 2:16 PM