minact-scn master-status: grec-scn:0x0000.0206dc80 gmin-scn:0x0000.0206dc31 gcalc-scn:0x0000.0206dc3b – KEBM: MMON action policy violation. ‘Block Cleanout Optim, Undo Segment Scan’ viol=1; err=12751


This message show when MMON process utilize undo tablespace heavily during high load in database. The minact-scn feature is introduced in 11g to enhance the block clean out of the tasks. When this error trigger, AWR statistics may not be gathered during the particular time because of large waits observed.

DDE rules only execution for: ORA 12751

*** 2021-12-24 23:54:37.759
----- START Event Driven Actions Dump ----
---- END Event Driven Actions Dump ----
----- START DDE Actions Dump -----
Executing SYNC actions
Executing ASYNC actions
----- START DDE Action: 'ORA_12751_DUMP' (Sync) -----
Runtime exceeded 300 seconds
Time limit violation detected at:
<-ssthrdmain()+265<-main()+201<-__libc_start_main()+244Current Wait Stack:

Wait details are printed in trace

Session Wait History:
    elapsed time of 0.000024 sec since current wait
 0: waited for 'KSV master wait'
    =0x0, =0x0, =0x0
    wait_id=34132 seq_num=34306 snap_id=1
    wait times: snap=0.000186 sec, exc=0.000186 sec, total=0.000186 sec
    wait times: max=infinite
    wait counts: calls=1 os=1
    occurred after 0.000077 sec of elapsed time
 1: waited for 'control file parallel write'
    files=0x2, block#=0x1, requests=0x2
    wait_id=34131 seq_num=34305 snap_id=1
    wait times: snap=0.000865 sec, exc=0.000865 sec, total=0.000865 sec
    wait times: max=infinite
    wait counts: calls=0 os=0
    occurred after 0.000284 sec of elapsed time
 2: waited for 'control file parallel write'
    files=0x2, block#=0x28, requests=0x2
    wait_id=34130 seq_num=34304 snap_id=1
    wait times: snap=0.000622 sec, exc=0.000622 sec, total=0.000622 sec
    wait times: max=infinite
    wait counts: calls=0 os=0


Disable minact-scn feature using any of the hidden parameter.

Warning: Do not disable the parameter in Exadata system due to dependency issues

kish@exdbx<>alter system set "_smu_debug_mode"=134217728;

System altered.


kish@exdbx<> alter system set "_enable_minscn_cr"=false scope=spfile;

System altered.

Leave a Reply