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Enhancement for investigating Log File Sync

edited Mar 2, 2019 4:01AM in Database Tuning (MOSC) 2 commentsAnswered

I am trying to understand the new statistic (enhancement)

Bug 12614085 : NEW STATS FOR INVESTIGATING LOG FILE SYNC AND LOG FILE PARALLEL WRITE RELATIONSH

The bug says:

This enhancement adds new "redo synch time overhead" statistics, which measure the difference between ideal and actual log file sync.

If these values are small, then large log file syncs can be attributed to outlier "log file parallel write" times.

Our AWR report shows:

log file sync Total Time:107,704s Avg:523ms

log file parallel write Total Time:2,241.46s Avg:28ms

redo synch time (usec) 107,604,694,205

redo synch time overhead (usec) 2,603,247,651

Can we attribute the high log file sync to log file parallel write?

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