I been dealing with log file sync and write complete wait issues.
Oracle Support is coming back with
Recommend to set sga_target to non-zero value to enable Automatic shared
memory management. This way, you will not run out of free blocks if needed
and in turn waits will reduce.
Also, there are 2 db writer processes, I suggest to increase it to 4. This
will ensure that the blocks gets copied to datafiles more quickly. This
will also help reduce the waits.
My understanding is there's no "golden rule" nor a "golden formula" to
increase DBWR. . That you would configure DBWR parameters only if we
really have an issue with DBWR Writes. Even then, you would first look at
the (SAN or NAS or DASD) Storage, I/O Channels and OS Parameters and
exhaust all other options before looking at these.
We are in the process of moving our redo onto there own drives and checking
if there are I/O issues.
I don't feel comfortable changing my production system to ASMM and
increasing my dbwr. before eliminate other areas.
What I do want to know is there a way to determine if DBWR need to be
increased? will the AWR report provide that information?
