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Frequent Checkpoint Issue

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Frequent Checkpoint Issue

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Hi

We are facing slowness in the database and when checked there were frequent checkpoint in the database. Not sure how the checkpoint occur so frequently. We have optimized BI cluster size as well as 3 APWs. Details are below

Progress Version 11.4

OS AIX 

DB Size 84GB

DB Blocksize 8192

Before-image block size: 16384 bytes
Before-image cluster size: 16384 kb

Though there were no flush noted during checkpoint. Does this frequent checkpoint can slowdown DB performance?

Any idea what can be done to minimize the checkpoint frequency? I didn't find any active or long running transaction. Bi blocksize and cluster size is already optimized. Is there any way to find which process generating checkpoint ?

O/p from promon -> R&D -> 3. Other Displays ... -> 4. Checkpoints

10/05/17        Checkpoints
10:05:49

Ckpt                                  ------ Database Writes ------
 No. Time        Len   Freq   Dirty   CPT Q    Scan   APW Q Flushes   Duration  Sync Time

4745 10:05:46      3      0      74     106       1       0       0       2.17       2.12

4744 10:05:16     30     30     112    1924      27       1       0       0.63       0.56
4743 10:04:36     40     40     107    1794      71       1       0       3.09       2.93
4742 10:03:39     55     57     190    1615     123      13       0       4.49       4.28
4741 10:03:15     22     24     629    2356      21       3       0       4.54       1.84
4740 10:03:00     15     15     144    2014       9       0       1       2.05       1.60
4739 10:02:44     15     16     106    1731      17       1       0       1.70       1.61
4738 10:02:29     14     15      24    2220       3       2       0       1.75       1.54

10/05/17        Checkpoints
11:18:12

Ckpt                                  ------ Database Writes ------
 No. Time        Len   Freq   Dirty   CPT Q    Scan   APW Q Flushes   Duration  Sync Time

4840 11:18:11      1      0    1620     406       0       0       0       1.03       0.59

4839 11:17:52     18     19     906    1823      16       1       0       6.61       4.09
4838 11:17:35     17     17    1146    2063      15       0       2       3.40       2.36
4837 11:17:19     16     16     706    1586      16       0      12       5.66       3.57
4836 11:17:07     12     12    1183    2044       4       0      66       1.05       0.91
4835 11:16:42     25     25     597    1520      17       0       0       5.99       4.61
4834 11:16:24     18     18    1180    2069      16       2      33       2.36       1.74
4833 11:16:09     15     15     668    1595      24       0       0       2.61       1.16
All Replies
  • > Does this frequent checkpoint can slowdown DB performance?

    Yes, exactly by checkpoint's duration. And almost 100% of checkpoint's duration is sync time.

  • Thanks for your response George. Any idea what can be done to minimize the checkpoint frequency? I didn't find any active or long running transaction. Bi blocksize and cluster size is already optimized. Is there any way to find which process generating checkpoint ?

  • > what can be done to minimize the checkpoint frequency?

    You can increase bi cluster size even more (by 2-4 times).

    > Is there any way to find which process generating checkpoint ?

    You can scan AI files. Process the scans by, for example, AiScanStat.p (check AiScanStat.Readme.txt):

    ftp.progress-tech.ru/.../