control file sequential read
This wait events occurs If one has all their control files on a disk with high disk I/O then access to control file for updating the SCN etc may result in this wait.Reading from the control file. This happens in many cases. For example, while
1)Making a backup of the control files
2)Sharing information (between instances) from the control file
3)Reading other blocks from the control files
4)Reading the header block
Wait Time: The wait time is the elapsed time of the read
In the above u see control file sequential read is on the top 5 list with wait class as System I/O. In this case if has come on the top as the no of transactions hitting the system have crossed 1000 Transactions Per Second(TPS) and the database is an high commit oriented OLTP system. That is the reason we see log file sync as one of the top 5 wait events.
Solution: Identify the Control file locations and try to place them on faster disks or less activity disks.
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