High Wait on System I/O on AWR

Question

Hi, I am currently looking into a performance issue on an OLTP database. Here are some statistics from the 60 minutes AWR report.
From the Load Profile, transaction / sec and transaction size is not too extreme.
I cannot figure out why does it take so long for the commit and write to the system.
When looking the system statistics IO wait time is 0.
Can anyone advise what could the issue here?
Thank you very much!!
Top 5 Timed Events Avg %Total
~~~~~~~~~~~~~~~~~~ wait Call
Event Waits Time (s) (ms) Time Wait Class
log file sync 145,634 5,359 37 74.0 Commit
db file parallel write 40,891 3,324 81 45.9 System I/O
log file parallel write 126,741 2,755 22 38.0 System I/O
CPU time 1,887 26.1
control file parallel write 1,613 137 85 1.9 System I/O
Avg
%Time Total Wait wait Waits
Wait Class Waits -outs Time (s) (ms) /txn
System I/O 172,667 .0 6,216 36 1.7
Commit 145,634 .0 5,359 37 1.5
Application 86,572 .0 21 0 0.9
Network 2,324,023 .0 8 0 23.2
User I/O 273 .0 6 21 0.0
Other 2,645 .0 3 1 0.0
Concurrency 4,756 .7 2 0 0.0
Configuration 1,454 .0 1 1 0.0
Load Profile
~~~~~~~~~~~~ Per Second Per Transaction
Redo size: 46,782.35 1,688.79
Logical reads: 5,463.19 197.21
Block changes: 422.23 15.24
Physical reads: 0.09 0.00
Physical writes: 44.53 1.61
User calls: 827.33 29.87
Parses: 435.42 15.72
Hard parses: 0.00 0.00
Sorts: 24.11 0.87
Logons: 0.01 0.00
Executes: 661.11 23.87
Transactions: 27.70
Wait Events DB/Inst: USRSE/usrse Snaps: 465-469
-> s - second
-> cs - centisecond - 100th of a second
-> ms - millisecond - 1000th of a second
-> us - microsecond - 1000000th of a second
-> ordered by wait time desc, waits desc (idle events last)
Avg
%Time Total Wait wait Waits
Event Waits -outs Time (s) (ms) /txn
log file sync 145,634 .0 5,359 37 1.5
db file parallel write 40,891 .0 3,324 81 0.4
log file parallel write 126,741 .0 2,755 22 1.3
control file parallel write 1,613 .0 137 85 0.0
SQL*Net break/reset to clien 86,572 .0 21 0 0.9
SQL*Net message to client 2,323,913 .0 8 0 23.2
db file sequential read 174 .0 6 33 0.0
enq: TX - contention 1,575 .0 2 1 0.0
os thread startup 8 .0 1 150 0.0
enq: HW - contention 1,412 .0 1 1 0.0
control file sequential read 3,422 .0 0 0 0.0
row cache lock 755 .0 0 1 0.0
buffer busy waits 3,627 .0 0 0 0.0
rdbms ipc reply 58 .0 0 7 0.0
cursor: pin S wait on X 34 91.2 0 9 0.0
latch free 8 .0 0 28 0.0
enq: SQ - contention 41 .0 0 1 0.0
latch: cache buffers chains 323 .0 0 0 0.0
LGWR wait for redo copy 802 .0 0 0 0.0
db file scattered read 94 .0 0 0 0.0
SQL*Net more data to client 64 .0 0 0 0.0
direct path write 5 .0 0 1 0.0
latch: In memory undo latch 9 .0 0 0 0.0
cursor: pin S 202 .0 0 0 0.0
SQL*Net more data from clien 46 .0 0 0 0.0
latch: redo writing 1 .0 0 0 0.0
SQL*Net message from client 2,323,916 .0 120,921 52 23.2
Streams AQ: qmn slave idle w 129 .0 3,510 27213 0.0
Streams AQ: qmn coordinator 258 50.0 3,510 13606 0.0
Streams AQ: waiting for time 1 100.0 3,469 ####### 0.0
class slave wait 9 .0 0 0 0.0
Operating System Statistics DB/Inst: USRSE/usrse Snaps: 465-469
Statistic Total
AVG_BUSY_TIME 41,929
AVG_IDLE_TIME 319,218
AVG_IOWAIT_TIME 0
AVG_SYS_TIME 12,531
AVG_USER_TIME 29,288
BUSY_TIME 336,295
IDLE_TIME 2,554,540
IOWAIT_TIME 0
SYS_TIME 101,141
USER_TIME 235,154
LOAD 1
OS_CPU_WAIT_TIME 164,400
RSRC_MGR_CPU_WAIT_TIME 0
VM_IN_BYTES 0
VM_OUT_BYTES 0
PHYSICAL_MEMORY_BYTES 33,727,037,440
NUM_CPUS 8
-------------------------------------------------------------

Answer 1

Please edit you post & add
tag (exactly as shown above) at the start & end of your post
since it is hard to read in present state
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