How to enable Exadata writeback Flashcache on cell storage ? (WriteThrough to WriteBack)

Steps to enabling the Flashcache mode:

This can be done in rolling as well as non-rolloing manner.

First check flashcache mode with below command on all cell servers with the use of dcli utility on DB node. It can be check on cell each server also with cellcli utility.

dbnode1#dcli -l root -g cellgroup "cellcli -e list cell detail" | grep "flashCacheMode"

10.156.110.10: flashCacheMode:          WriteThrough
10.156.110.11: flashCacheMode:          WriteThrough
10.156.110.12: flashCacheMode:          WriteThrough
10.156.110.13: flashCacheMode:          WriteThrough
10.156.110.14: flashCacheMode:          WriteThrough
10.156.110.15: flashCacheMode:          WriteThrough
10.156.110.16: flashCacheMode:          WriteThrough

Step-1
Also we can find flashcache mode in each cell by executing below command:

cellcli>list cell detail

flashCacheMode: WriteThrough     --->Currently flashCacheMode configured as WriteThrough

Step-2
Now drop flashcache on each cell server: (If you are following rolling manner then do one by one on each cell server)

cellcli> drop flashcache

Step-3
Be sure asmdeactivationoutcome is YES before disabling grid disk

CellCLI> list griddisk attributes name,asmmodestatus,asmdeactivationoutcome

Step-4

Inactive all the grid Disk 

CellCLI> alter griddisk all inactive

Step-5
Stop Cell Server services 

CellCLI> alter cell shutdown services cellsrv
Stopping CELLSRV services...
 The SHUTDOWN of CELLSRV services was successful

Step-6 
Change the FlashCacheMode parameter 

CellCLI> alter cell flashCacheMode=writeback
 Cell testcel03 successfully altered

Step-7
Start the cell server Services  

CellCLI> alter cell startup services cellsrv

Starting CELLSRV services...
 The STARTUP of CELLSRV services was successful

Step-8
Activate all grid disks

CellCLI> alter griddisk all active

Step -9
Check griddisk status

CellCLI> list griddisk attributes name, asmmodestatus --------wait to become online

Step -10
Create Flash Cache

CellCLI> create flashcache all

Step -11
Check the flashCacheMode parameter, It should change from WriteThrough to writeback

CellCLI> list cell detail --To check Flashcache mode on single cell server

flashCacheMode:          writeback

You can check it on all the cell server with dcli utility on DB node.

# dcli -l root -g cellgroup "cellcli -e list cell detail" | grep "flashCacheMode"
10.156.110.10: flashCacheMode:          writeback
10.156.110.11: flashCacheMode:          writeback
10.156.110.12: flashCacheMode:          writeback
10.156.110.13: flashCacheMode:          writeback
10.156.110.14: flashCacheMode:          writeback
10.156.110.15: flashCacheMode:          writeback

10.156.110.16: flashCacheMode:          writeback