15 December 2020
0 Comment
How to Enable Oracle Exadata Write Back Smart Flash Cache
Write-back flash caching is faster than writing to hard disks, a write back flash cache, used to improve write-intensive operations, is useful for running heavy-duty jobs in a database. According to Oracle, depending on the application, write performance to disk can be 20 times faster (measured at input / output operations per second (IOPS)) and can have 10 times more write IOPS than disk.
I’m following the steps below to enable write back for exadata flash cache.
dcli -g cell_group -l root hostname
dcli -g cell_group -l root cellcli -e “list cell attributes flashcachemode”
dcli -g cell_group -l root cellcli -e list griddisk attributes asmdeactivationoutcome, asmmodestatus
dcli -g cell_group -l root cellcli -e list flashcache detail
- Drop the flash cache on that cell
cellcli -e drop flashcache
- Check if ASM will be OK if the grid disks go OFFLINE. The following command should return ‘Yes’ for the grid disks being listed:
cellcli -e list griddisk attributes name,asmmodestatus,asmdeactivationoutcome
- Inactivate the griddisk on the cell
cellcli –e alter griddisk all inactive
- Shut down cellsrv service
cellcli -e alter cell shutdown services cellsrv
- Set the cell flashcache mode to writeback
cellcli -e “alter cell flashCacheMode=writeback”
- Restart the cellsrv service
cellcli -e alter cell startup services cellsrv
- Reactivate the griddisks on the cell
cellcli –e alter griddisk all active
- Verify all grid disks have been successfully put online using the following command:
cellcli -e list griddisk attributes name, asmmodestatus
- Recreate the flash cache
cellcli -e create flashcache all
- Check the status of the cell to confirm that it’s now in WriteBack mode:
cellcli -e list cell detail | grep flashCacheMode
- Repeat these same steps again on the next cell. However, before taking another storage server offline, execute the following making sure ‘asmdeactivationoutcome’ displays YES:
cellcli -e list griddisk attributes name,asmmodestatus,asmdeactivationoutcome
dcli -g cell_group -l root hostname
dcli -g cell_group -l root cellcli -e “list cell attributes flashcachemode”
dcli -g cell_group -l root cellcli -e list griddisk attributes asmdeactivationoutcome, asmmodestatus
dcli -g cell_group -l root cellcli -e list flashcache detail
- Drop the flash cache on that cell
cellcli -e drop flashcache
- Check if ASM will be OK if the grid disks go OFFLINE. The following command should return ‘Yes’ for the grid disks being listed:
cellcli -e list griddisk attributes name,asmmodestatus,asmdeactivationoutcome
- Inactivate the griddisk on the cell
cellcli –e alter griddisk all inactive
- Shut down cellsrv service
cellcli -e alter cell shutdown services cellsrv
- Set the cell flashcache mode to writeback
cellcli -e “alter cell flashCacheMode=writeback”
- Restart the cellsrv service
cellcli -e alter cell startup services cellsrv
- Reactivate the griddisks on the cell
cellcli –e alter griddisk all active
- Verify all grid disks have been successfully put online using the following command:
cellcli -e list griddisk attributes name, asmmodestatus
- Recreate the flash cache
cellcli -e create flashcache all
- Check the status of the cell to confirm that it’s now in WriteBack mode:
cellcli -e list cell detail | grep flashCacheMode
flashCacheMode: WriteBack- Repeat these same steps again on the next cell. However, before taking another storage server offline, execute the following making sure ‘asmdeactivationoutcome’ displays YES:
cellcli -e list griddisk attributes name,asmmodestatus,asmdeactivationoutcome
DATAC1_CD_00_sp000cel01 ONLINE Yes
DATAC1_CD_01_sp000cel01 ONLINE Yes
DATAC1_CD_02_sp000cel01 ONLINE Yes
DATAC1_CD_03_sp000cel01 ONLINE Yes
DATAC1_CD_04_sp000cel01 ONLINE Yes
DATAC1_CD_05_sp000cel01 ONLINE Yes
DATAC1_CD_06_sp000cel01 ONLINE Yes
DATAC1_CD_07_sp000cel01 ONLINE Yes
DATAC1_CD_08_sp000cel01 ONLINE Yes
DATAC1_CD_09_sp000cel01 ONLINE Yes
DATAC1_CD_10_sp000cel01 ONLINE Yes
DATAC1_CD_11_sp000cel01 ONLINE Yes
RECOC1_CD_00_sp000cel01 ONLINE Yes
RECOC1_CD_01_sp000cel01 ONLINE Yes
RECOC1_CD_02_sp000cel01 ONLINE Yes
RECOC1_CD_03_sp000cel01 ONLINE Yes
RECOC1_CD_04_sp000cel01 ONLINE Yes
RECOC1_CD_05_sp000cel01 ONLINE Yes
RECOC1_CD_06_sp000cel01 ONLINE Yes
RECOC1_CD_07_sp000cel01 ONLINE Yes
RECOC1_CD_08_sp000cel01 ONLINE Yes
RECOC1_CD_09_sp000cel01 ONLINE Yes
RECOC1_CD_10_sp000cel01 ONLINE Yes
RECOC1_CD_11_sp000cel01 ONLINE YesCellCLI> list cell detail
name: sp000cel01
accessLevelPerm: remoteLoginEnabled
bbuStatus: normal
cellVersion: OSS_19.2.9.0.0_LINUX.X64_191211.1
cpuCount: 40/40
diagHistoryDays: 7
doNotServiceLEDStatus: off
fanCount: 8/8
fanStatus: normal
flashCacheMode: WriteBack
httpsAccess: ALL
id: 1806XC20CL
interconnectCount: 2
interconnect1: ib0
interconnect2: ib1
[root@sp000cel01 ~]# cellcli -e list griddisk attributes name,cachingpolicy,cachedby
DATAC1_CD_00_sp000cel01 default FD_01_ru02
DATAC1_CD_01_sp000cel01 default FD_00_ru02
DATAC1_CD_02_sp000cel01 default FD_02_ru02
DATAC1_CD_03_sp000cel01 default FD_01_ru02
DATAC1_CD_04_sp000cel01 default FD_00_ru02
DATAC1_CD_05_sp000cel01 default FD_03_ru02
DATAC1_CD_06_sp000cel01 default FD_03_ru02
DATAC1_CD_07_sp000cel01 default FD_02_ru02
DATAC1_CD_08_sp000cel01 default FD_01_ru02
DATAC1_CD_09_sp000cel01 default FD_02_ru02
DATAC1_CD_10_sp000cel01 default FD_03_ru02
DATAC1_CD_11_sp000cel01 default FD_00_ru02
RECOC1_CD_00_sp000cel01 none
RECOC1_CD_01_sp000cel01 none
RECOC1_CD_02_sp000cel01 none
RECOC1_CD_03_sp000cel01 none
RECOC1_CD_04_sp000cel01 none
RECOC1_CD_05_sp000cel01 none
RECOC1_CD_06_sp000cel01 none
RECOC1_CD_07_sp000cel01 none
RECOC1_CD_08_sp000cel01 none
RECOC1_CD_09_sp000cel01 none
RECOC1_CD_10_sp000cel01 none
RECOC1_CD_11_sp000cel01 none
Tags: