How can I enable the Exadata Write Back Flash cache ?

Exadata storage version 11.2.3.2.1 is the minimum version required to use this write back flash cache option.

Oracle rdbms software 11.2.0.3 BP9  or later is necessary.

If you find in AWR reports “free buffer waits” or high I/O time for write operation ,you should consider using write-back option.

Steps for Enabling Write back flash cache:

First of all,you don’t need the stop CRS or database (This is ROLLING method) ,you can do it cell by cell.

##

[root@owtcel01 ~]# dcli -l root -g cell_group "cellcli -e list cell detail" | grep "flashCacheMode"
 owtcel01: flashCacheMode: WriteThrough
 owtcel02: flashCacheMode: WriteThrough
 owtcel03: flashCacheMode: WriteThrough
 owtcel04: flashCacheMode: WriteThrough
 owtcel05: flashCacheMode: WriteThrough
 owtcel06: flashCacheMode: WriteThrough

##

</pre>
CellCLI> list cell detail
 name: owtcel04
 bbuTempThreshold: 60
 bbuChargeThreshold: 800
 bmcType: IPMI
 cellVersion: OSS_11.2.3.2.1_LINUX.X64_130109
 cpuCount: 24
 diagHistoryDays: 7
 fanCount: 8/8
 fanStatus: normal
 flashCacheMode: WriteThrough--------------------------------Current Mode
 id: 1250FM5062
 interconnectCount: 3
 interconnect1: bondib0
 iormBoost: 0.4
 ipaddress1: 192.168.30.8/22
 kernelVersion: 2.6.32-400.11.1.el5uek
 locatorLEDStatus: off
 makeModel: Oracle Corporation SUN FIRE X4270 M3 SAS
 metricHistoryDays: 7
 offloadEfficiency: 7,323.6
 powerCount: 2/2
 powerStatus: normal
 releaseVersion: 11.2.3.2.1
 releaseTrackingBug: 14522699
 smtpFrom: "Exadata OWT HALF"
 smtpFromAddr: unixasr@***
 smtpServer: ***
 smtpToAddr: unixasr@***
 status: online
 temperatureReading: 19.0
 temperatureStatus: normal
 upTime: 28 days, 14:34
 cellsrvStatus: running
 msStatus: running
 rsStatus: running
<pre>

##

drop flashcache

</pre>
 CellCLI> drop flashcache
 Flash cache owtcel03_FLASHCACHE successfully dropped
<pre>

##

Be sure asmdeactivationoutcome is YES  is before disabling grid disk

</pre>
CellCLI> list griddisk attributes name,asmmodestatus,asmdeactivationoutcome
 DATA_OWT_CD_00_owtcel03 ONLINE Yes
 DATA_OWT_CD_01_owtcel03 ONLINE Yes
 DATA_OWT_CD_02_owtcel03 ONLINE Yes
 DATA_OWT_CD_03_owtcel03 ONLINE Yes
 DATA_OWT_CD_04_owtcel03 ONLINE Yes
 DATA_OWT_CD_05_owtcel03 ONLINE Yes
 DATA_OWT_CD_06_owtcel03 ONLINE Yes
 DATA_OWT_CD_07_owtcel03 ONLINE Yes
 DATA_OWT_CD_08_owtcel03 ONLINE Yes
 DATA_OWT_CD_09_owtcel03 ONLINE Yes
 DATA_OWT_CD_10_owtcel03 ONLINE Yes
 DATA_OWT_CD_11_owtcel03 ONLINE Yes
 DBFS_DG_CD_02_owtcel03 ONLINE Yes
 DBFS_DG_CD_03_owtcel03 ONLINE Yes
 DBFS_DG_CD_04_owtcel03 ONLINE Yes
 DBFS_DG_CD_05_owtcel03 ONLINE Yes
 DBFS_DG_CD_06_owtcel03 ONLINE Yes
 DBFS_DG_CD_07_owtcel03 ONLINE Yes
 DBFS_DG_CD_08_owtcel03 ONLINE Yes
 DBFS_DG_CD_09_owtcel03 ONLINE Yes
 DBFS_DG_CD_10_owtcel03 ONLINE Yes
 DBFS_DG_CD_11_owtcel03 ONLINE Yes
 RECO_OWT_CD_00_owtcel03 ONLINE Yes
 RECO_OWT_CD_01_owtcel03 ONLINE Yes
 RECO_OWT_CD_02_owtcel03 ONLINE Yes
 RECO_OWT_CD_03_owtcel03 ONLINE Yes
 RECO_OWT_CD_04_owtcel03 ONLINE Yes
 RECO_OWT_CD_05_owtcel03 ONLINE Yes
 RECO_OWT_CD_06_owtcel03 ONLINE Yes
 RECO_OWT_CD_07_owtcel03 ONLINE Yes
 RECO_OWT_CD_08_owtcel03 ONLINE Yes
 RECO_OWT_CD_09_owtcel03 ONLINE Yes
 RECO_OWT_CD_10_owtcel03 ONLINE Yes
 RECO_OWT_CD_11_owtcel03 ONLINE Yes
<pre>

##

</pre>
CellCLI> alter griddisk all inactive
 GridDisk DATA_OWT_CD_00_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_01_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_02_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_03_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_04_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_05_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_06_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_07_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_08_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_09_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_10_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_11_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_02_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_03_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_04_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_05_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_06_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_07_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_08_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_09_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_10_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_11_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_00_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_01_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_02_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_03_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_04_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_05_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_06_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_07_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_08_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_09_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_10_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_11_owtcel03 successfully altered
<pre>

##

</pre>
CellCLI> alter cell shutdown services cellsrv

Stopping CELLSRV services...
 The SHUTDOWN of CELLSRV services was successful

CellCLI> alter cell flashCacheMode=writeback
 Cell owtcel03 successfully altered

CellCLI> alter cell startup services cellsrv

Starting CELLSRV services...
 The STARTUP of CELLSRV services was successful
<pre>

 

</pre>
 CellCLI> alter griddisk all active
 GridDisk DATA_OWT_CD_00_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_01_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_02_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_03_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_04_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_05_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_06_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_07_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_08_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_09_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_10_owtcel03 successfully altered
 GridDisk DATA_OWT_CD_11_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_02_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_03_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_04_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_05_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_06_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_07_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_08_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_09_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_10_owtcel03 successfully altered
 GridDisk DBFS_DG_CD_11_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_00_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_01_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_02_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_03_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_04_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_05_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_06_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_07_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_08_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_09_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_10_owtcel03 successfully altered
 GridDisk RECO_OWT_CD_11_owtcel03 successfully altered
 CellCLI> list griddisk attributes name, asmmodestatus ----wait become online
 DATA_OWT_CD_00_owtcel03 SYNCING
 DATA_OWT_CD_01_owtcel03 SYNCING
 DATA_OWT_CD_02_owtcel03 SYNCING
 DATA_OWT_CD_03_owtcel03 SYNCING
 DATA_OWT_CD_04_owtcel03 SYNCING
 DATA_OWT_CD_05_owtcel03 SYNCING
 DATA_OWT_CD_06_owtcel03 SYNCING
 DATA_OWT_CD_07_owtcel03 SYNCING
 DATA_OWT_CD_08_owtcel03 SYNCING
 DATA_OWT_CD_09_owtcel03 SYNCING
 DATA_OWT_CD_10_owtcel03 SYNCING
 DATA_OWT_CD_11_owtcel03 SYNCING
 DBFS_DG_CD_02_owtcel03 SYNCING
 DBFS_DG_CD_03_owtcel03 SYNCING
 DBFS_DG_CD_04_owtcel03 SYNCING
 DBFS_DG_CD_05_owtcel03 SYNCING
 DBFS_DG_CD_06_owtcel03 SYNCING
 DBFS_DG_CD_07_owtcel03 SYNCING
 DBFS_DG_CD_08_owtcel03 SYNCING
 DBFS_DG_CD_09_owtcel03 SYNCING
 DBFS_DG_CD_10_owtcel03 SYNCING
 DBFS_DG_CD_11_owtcel03 SYNCING
 RECO_OWT_CD_00_owtcel03 SYNCING
 RECO_OWT_CD_01_owtcel03 SYNCING
 RECO_OWT_CD_02_owtcel03 SYNCING
 RECO_OWT_CD_03_owtcel03 SYNCING
 RECO_OWT_CD_04_owtcel03 SYNCING
 RECO_OWT_CD_05_owtcel03 SYNCING
 RECO_OWT_CD_06_owtcel03 SYNCING
 RECO_OWT_CD_07_owtcel03 SYNCING
 RECO_OWT_CD_08_owtcel03 SYNCING
 RECO_OWT_CD_09_owtcel03 SYNCING
 RECO_OWT_CD_10_owtcel03 SYNCING
 RECO_OWT_CD_11_owtcel03 SYNCING</pre>
CellCLI> create flashcache all
 Flash cache owtcel03_FLASHCACHE successfully created

CellCLI> list cell detail
 name: owtcel03
 bbuTempThreshold: 60
 bbuChargeThreshold: 800
 bmcType: IPMI
 cellVersion: OSS_11.2.3.2.1_LINUX.X64_130109
 cpuCount: 24
 diagHistoryDays: 7
 fanCount: 12/12
 fanStatus: normal
 flashCacheMode: writeback------------------Now mode become WRITEBACK
 id: 1110FMM1DG
 interconnectCount: 3
 interconnect1: bondib0
 iormBoost: 0.0
 ipaddress1: 192.168.30.7/22
 kernelVersion: 2.6.32-400.11.1.el5uek
 locatorLEDStatus: off
 makeModel: Oracle Corporation SUN FIRE X4270 M2 SERVER SAS
 metricHistoryDays: 7
 notificationMethod: mail
 notificationPolicy: critical,warning,clear
 offloadEfficiency: 5,379.5
 powerCount: 2/2
 powerStatus: normal
 releaseVersion: 11.2.3.2.1
 releaseTrackingBug: 14522699
 smtpFrom: "Exadata OWT quarter"
 smtpFromAddr:***
 smtpPort: 25
 smtpPwd: ******
 smtpServer:***
 smtpToAddr: unixasr@**
 smtpUser:
 smtpUseSSL: FALSE
 snmpSubscriber: host=10.**,port=162,community=public,type=asr
 status: online
 temperatureReading: 20.0
 temperatureStatus: normal
 upTime: 28 days, 13:52
 cellsrvStatus: running
 msStatus: running
 rsStatus: running
 ####

Do these steps  for all exadata cells and then check the status:

[root@owtcel01 ~]# dcli -l root -g cell_group "cellcli -e list cell detail" | grep "flashCacheMode"
 owtcel01: flashCacheMode: WriteBack
 owtcel02: flashCacheMode: WriteBack
 owtcel03: flashCacheMode: WriteBack
 owtcel04: flashCacheMode: WriteBack
 owtcel05: flashCacheMode: WriteBack
 owtcel06: flashCacheMode: WriteBack

&nbsp;
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