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Smart Flash Cache in Oracle Exadata -2

Hi,

I will explain Smart Flash cache feature of Oracle Exadata in this article.

 

Read previous article before this.

Smart Flash Cache in Oracle Exadata -1

 

 

 

Exadata supports two types of flash cache mode: Write Through and Write Back. Write Through is default mode of Exadata.

 

Write Through

 

 

 

Write Back

Exadata Storage Software 11.2.3.2.0 version in the Write back mode  with write-intensive environments is selected to be advantageous when selected.

Exadata Storage Software 11.2.3.2.0 version with write-intensive environments in the Write back mode is selected to be advantageous when selected. When this mode is activated, the following actions are taken when the write operation is performed.

 

Write back mode in the Exadata Storage Software 11.2.3.2.0 have been more advantageous in the write-intensive databases. When this mode is activated, the following actions are done when the write operation is performed.

 

 

 

 

You can learn which mode is used in Storage Server with the following query.

 

Or you can learn it from detailed features of Cell as follows.

Yada Cell in detaylı özelliklerinden de aşağıdaki gibi görebilirsiniz.

 

 

The following steps can be used to activate Writeback mode in Rolling mode.

CellCLI> drop flashcache

CellCLI> list griddisk attributes name,asmmodestatus,asmdeactivationoutcome

CellCLI> alter griddisk all inactive

CellCLI> alter cell shutdown services cellsrv

CellCLI> alter cell flashCacheMode=WriteBack

CellCLI> alter cell startup services cellsrv

CellCLI> alter griddisk all active

CellCLI> create flashcache all

CellCLI> list cell detail [OR] list cell attributes flashCacheMode

 

We need to perform above steps on each Cell Server. We can also do this in non-Rolling mode. However, when done in non-rolling mode, we need to have full downtime.

 

 

Writeback mode provides serious advantage to write to Cache/memory instead of disk. This mode is very suitable in database where writing operations are more than read requests. In general Write back is suitable for OLTP database, and Write Through is perfect for OLAP environments.

 

 
 

Do you want to learn Oracle Database for Beginners, then read the following articles.

https://ittutorial.org/oracle-database-19c-tutorials-for-beginners/

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