Moiz, thank you. We did move the redo logs and our SGA is sized
correctly. I feel comfortable that our SGA is sized correctly. Years
back we ran into our pools being over 90% usage and once we clean them up
we saw. a major improvement. I now have jobs run daily that checks the %
of our pools.
Thinking we need additional disk and possible some kernel patches are
missing. I have no intention to switch to ASMM on my production system.
We are using ZSF file system and waiting on Oracle Hardware team before
making any changes. See what they find.
How many DBWR are you using?
On Thu, Oct 8, 2015 at 5:00 PM, Moizuddin Arshad Mohamed <
moizarshad@xxxxxxxxx> wrote:
Hi Michael,
I have been in to the similar issue sometime back. Seems to be almost same
issue. What file system are you using?
We increased the SGA, DBWR and also redo logs were moved to a different
disk, faster.
We were using Veritas ZFS file systems. After trying all these, still log
file sync issue continues......
Later Oracle export from ZFS was involved, they applied some kernel level
patches (not sure as I am not a sys admin) but prominently, the ZFS file
system disk of pools was above 90% usage.... Oracle asked us to get this
percentage lower, so system admin added disks, as soon as the percentage
was lower than 80%, log file sync issue resolved.
Hope this would help.
Thanks,
Moiz
On Thu, Oct 8, 2015 at 3:41 PM, Michael Calisi <oracle455@xxxxxxxxx>
wrote:
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?
