What action(s) must you perform to create Flash-based grid disks?
A.
None – they are created by default
B.
Issue the CREATE DISK. . FLASHDISK command after initial setup of the cell I
C.
Issue DROP FLASHCACHE and then CREATE GRIDDISK FLASHDISK commands
D.
Issue the DROP FLASHCACHE and CREATE FLASHCELLDISK commands
Explanation:
The default way to deal with the Flash Storage is to use it completely as Flash
Cache. You may think of Flash Cache as a prolongation of the Database Buffer Cache. It is
populated automatically by the system with objects deemed useful to cache them.
The second possibility to deal with the Flash Storage is to take a part of it for building ASM
diskgroups upon. All files on these ASM diskgroups will then reside permanently on Flash Storage:
CellCLI> drop flashcache
Flash cache exa5cel01_FLASHCACHE successfully dropped
CellCLI> create flashcache all size=100g
Flash cache exa5cel01_FLASHCACHE successfully created
CellCLI> create griddisk all flashdisk prefix=flashdrive
GridDisk flashdrive_FD_00_exa5cel01 successfully created
GridDisk flashdrive_FD_01_exa5cel01 successfully created
GridDisk flashdrive_FD_02_exa5cel01 successfully createdGridDisk flashdrive_FD_03_exa5cel01 successfully created
GridDisk flashdrive_FD_04_exa5cel01 successfully created
GridDisk flashdrive_FD_05_exa5cel01 successfully created
GridDisk flashdrive_FD_06_exa5cel01 successfully created
GridDisk flashdrive_FD_07_exa5cel01 successfully created
GridDisk flashdrive_FD_08_exa5cel01 successfully created
GridDisk flashdrive_FD_09_exa5cel01 successfully created
GridDisk flashdrive_FD_10_exa5cel01 successfully created
GridDisk flashdrive_FD_11_exa5cel01 successfully created
GridDisk flashdrive_FD_12_exa5cel01 successfully created
GridDisk flashdrive_FD_13_exa5cel01 successfully created
GridDisk flashdrive_FD_14_exa5cel01 successfully created
GridDisk flashdrive_FD_15_exa5cel01 successfully created
The Flash Cache for this cell is now reduced to 100 GB; all means “upon all 16 Flash Drives” here.
I
Note: User data is automatically cached using the default caching behavior. Optionally, a portion
of the cache can be reserved and used as logical flash disks. These flash disks are treated like
any Exadata cell disk in the Exadata cell except they actually reside and are stored as non-volatile
disks in the cache. For each Exadata cell the space reserved for flash disks is allocated across
sixteen (16) cell disks – 4 cell disks per flash card. Grid disks are created on these flash-based cell
disks and the grid disks are assigned to an Automatic Storage Management (ASM) diskgroup. The
best practice would be to reserve the same amount of flash on each Exadata cell for flash disks
and have the ASM diskgroup spread evenly across the Exadata cells in the configuration just as
you would do for regular Exadata grid disks. This will evenly distribute the flash I/O load across the
Exadata cells and flash.
Incorrect:
A: User data is automatically cached using the default caching behavior. Optionally, a portion of
the cache can be reserved and used as logical flash disks.
http://uhesse.wordpress.com/2011/02/02/exadata-part-iv-flash-cache/