Oracle AWR

[Anonymous]

Hi Team,

when we investigate the I/O issues of the AWR report, the "Top 10 Foreground Events by Total Wait Time" showed below.

Which factors related to the IO performance we should focus on and what they means? thanks.

Event                                     Waits       Total Wait Time (sec)      Wait Avg(ms) %       DB time          Wait Class

DB CPU                                                 344.7                                                                 46.3

local write wait                       54,114     193.8                                                                 26.0              User I/O

db file sequential read          126,267    56.2                                     0                             7.6                User I/O

[zhaos2]

The 'db file sequential read' is disk I/O related.  The 'Wait Avg' > 20ms is unacceptable, obviously it is not an issue in your case.

If the 'db file sequential read' caused large waiting time (>20ms) you can find more detail information about the blocks accessed in V$session_wait, V$session_event, and dba_extents.

DB file sequential read (%)