High-disk IOPS (I/Os per second) rates are leading to longer execution times.
Which three approaches would you use to improve this scenario?
A.
Enable Write-Back Flash Cache due to heavy DBWR usage.
B.
Enable Write-Back Flash Cache due to heavy LGWR usage.
C.
Swap hard disks to High Capacity disks.
D.
Tune the application to reduce I/O requests.
E.
LeverageIORM to give priority to critical workloads.
Explanation:
B (not A): Smart Flash Logging is a recent Exadata enhancement that provides
physical disk redo write relief in times of high LGWR activity; alone, probably not a driver for
Exadata.
A,D,E
The correct answer is ADE
B is not a correct answer. Smart Flash Log provides a high-performance, low-latency, reliable temporary store for redo log writes.
B,D,E
because the feature Write-Back Flash Cache is designed for log writer and not dbwr.
A D E
First is Exadata Smart Flash Cache which provides the capability to stage active database objects in flash. Second is the Exadata Smart Flash Logging which speeds the critical function of database logging.
http://www.oracle.com/technetwork/articles/database/exadata-write-back-flash-2179184.html
its B,D,E
As mentioned in the doc provided by Vaheed it’s ADE .I agree also with Syed .
ADE
It is important to note that Smart Flash Logging improves latency of log write operations, but it does not improve total disk throughput. If an application is bottlenecked on disk throughput, then Smart Flash Logging can provide little benefit because log response time is not the limiting factor to performance.
see: https://docs.oracle.com/cd/E50790_01/doc/doc.121/e50471/concepts.htm#SAGUG20317
A: Enable Write-Back Flash Cache due to heavy DBWR usage.
B: Enable Write-Back Flash Cache due to heavy LGWR usage.
E: Leverage IORM to give priority to critical workloads
Explanation:
Write-Back Flash Cache Benefits:
It improves the write intensive operations because writing to flash cache is much faster than writing to Hard disks.
Write-Back Flash Cache transparently accelerates reads and writes for all workloads for OLTP (faster random reads and writes) and DW (faster sequential smart scans).
Write-Back Flash Cache reduce latency of redo log writes when it shares disks with data. It’s true that you can use the Smart Flash Log for redo operations, but if you not use, the Write-Back Flash Cache will performance the redo operations.
IORM to give priorities.
http://www.oracle.com/technetwork/articles/database/exadata-write-back-flash-2179184.html
The answer would be A,D,E
B cannot be the answer because, Write-Back Flash Cache is only for DBWR. LGWR uses Flash Log and not Flash Cache. So for heavy LGWR usage, we need to verify that Flash Log exists and flashLog=on for the database in the IORM dbPlan.