Exadata Flash Cache - Management

Total size of Flash CellCLI>  list flashcache attributes effectiveCacheSize
         5.82122802734375T

Flashcache Mode:

 [root@Cellc01-adm ~]# su - celladmin
cellcli
CellCLI>  list cell attributes flashCacheMode,status
         WriteThrough    online

> list celldisk where disktype=flashdisk
> list physicaldisk FLASH_1_1 detail

List PhysicalDisk for FlashCache:

CellCLI> list physicaldisk attributes name, disktype, makemodel, physicalrpm, physicalport, status
     8:0           HardDisk      "HGST    H7240AS60SUN4.0T"                              normal
     8:1           HardDisk      "HGST    H7240AS60SUN4.0T"                              normal
     8:2           HardDisk      "HGST    H7240AS60SUN4.0T"                              normal
     8:3           HardDisk      "HGST    H7240AS60SUN4.0T"                              normal
     8:4           HardDisk      "HGST    H7240AS60SUN4.0T"                              normal
     8:5           HardDisk      "HGST    H7240AS60SUN4.0T"                              normal
     8:6           HardDisk      "HGST    H7240AS60SUN4.0T"                              normal
     8:7           HardDisk      "HGST    H7240AS60SUN4.0T"                              normal
     8:8           HardDisk      "HGST    H7240AS60SUN4.0T"                              normal
     8:9           HardDisk      "HGST    H7240AS60SUN4.0T"                              normal
     8:10          HardDisk      "HGST    H7240AS60SUN4.0T"                              normal
     8:11          HardDisk      "HGST    H7240AS60SUN4.0T"                              normal
     FLASH_1_1     FlashDisk     "Oracle Flash Accelerator F160 PCIe Card"               normal
     FLASH_2_1     FlashDisk     "Oracle Flash Accelerator F160 PCIe Card"               normal
     FLASH_4_1     FlashDisk     "Oracle Flash Accelerator F160 PCIe Card"               normal
     FLASH_5_1     FlashDisk     "Oracle Flash Accelerator F160 PCIe Card"               normal

Flashcache Size/Cell:
CellCLI> list flashcache detail
         name:                   iorssc01_adm_FLASHCACHE
         cellDisk:               FD_00_Cell01_adm,FD_03_Cell01_adm,FD_02_Cell_adm,FD_01_Cell01_adm
         creationTime:           2016-05-18T13:33:23+08:00
         degradedCelldisks:
         effectiveCacheSize:     5.82122802734375T
         id:                     e7584ff9-a481-4033-ac83-862d3e7bdb9b
         size:                   5.82122802734375T
         status:                 normal

Report Exadata Flashcache usage 

# dcli -g ~/all_cell_group -l root cellcli -e list flashcache attributes size
10.333.444.23: 5.82122802734375T
10.333.444.24: 5.82122802734375T
10.333.444.25: 5.82122802734375T

# dcli -g /root/all_cell_group -l root "cellcli -e  'list metriccurrent fc_by_dirty,fc_by_used,fc_by_allocated'" > /tmp/log2
[root@ :~]
# cat /tmp/log2
10.333.444.23: FC_BY_DIRTY             FLASHCACHE      0.000 MB
10.333.444.23: FC_BY_USED            FLASHCACHE      3,810,938 MB
10.333.444.23: FC_BY_ALLOCATED       FLASHCACHE      3,905,503 MB

10.333.444.24: FC_BY_DIRTY           FLASHCACHE      0.000 MB
10.333.444.24: FC_BY_USED            FLASHCACHE      3,782,954 MB
10.333.444.24: FC_BY_ALLOCATED       FLASHCACHE      3,877,155 MB

10.333.444.25: FC_BY_DIRTY           FLASHCACHE      0.000 MB
10.333.444.25: FC_BY_USED            FLASHCACHE      3,756,996 MB
10.333.444.25: FC_BY_ALLOCATED       FLASHCACHE      3,854,544 MB

Exadata Smart FlashLog

Exadata Smart Flash Cache, Exadata Smart Flash Log provides a mechanism for improving the latency of database redo log write operations. Exadata Smart Flash Log uses a small portion of high-performance flash memory as temporary storage to facilitate low latency redo log writes. By default, Exadata Smart Flash Log uses 32 MB on each flash-based cell disk, for a total of 512 MB on each Exadata Storage Server.

CellCLI> list flashlog detail
         name:                   Cell01_adm_FLASHLOG
         cellDisk:               FD_01_Cell01_adm,FD_00_Cell_adm
         creationTime:           2015-04-08T13:08:22+08:00
         degradedCelldisks:
         effectiveSize:          512M
         efficiency:             100.0
         id:                     ea9515cf-1360-4157-bb39-fe4e56gg-cc55
         size:                   512M
         status:                 normal
 
# cellcli -e create flashlog all
[celladmin@Cell01-adm ~]$ cellcli -e list flashlog
         Cell01_adm_FLASHLOG   normal
[celladmin@Cell-adm ~]$ cellcli -e list flashlog attributes name,size
         Cell01_adm_FLASHLOG   512M

[Note: 32*16=512M] | each disk device is 32M and there are 16 Disks.




Columnar Flash caching:

Exadata Hybrid Columnar compression - data is automatically transformed into pure columner format for anylytics format in flash cache of 1MB of  blocks. This is enabled by default.

Exadata Patch releae : 12.1.2
Database release: 12.1.0.2

This works by first writing all the block headers to an array, then writing all the CU headers to an array, finally writing all the Column 1 column-level-CUs, then writing all the Column2 column-level-CUs etc.
 
Source: From Oracle  Document