Which four statements are true about Exadata Smart Flash Cache?
A.
Smart Scan will always be done for I/Os to flash based griddisks.
B.
Flash based ASM diskgroups may share space with the Flash Cache on the flashdisks.
C.
Single block reads can benefit from Smart Flash Cache.
D.
Smart Scan will never be done for I/Os to flash based griddisks.
E.
Multiblock reads can benefit from Smart Flash Cache.
F.
Smart Flash Logs reduce the size of Smart Flash Cache.
Explanation:
B: *Grid disks (the logical disks
that reside on physical cell disks) are created on these flash-based cell disks and the grid disks
areassigned 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.
Note:
*The Exadata
Storage Server comes with a substantial amount of flash storage. A small amount is allocated for
database logging and the remainder will be used for caching user data
A is wrong. flash based grid disk is no difference than hard-disk based grid disk. So smart scan may not always true
B is right. Flash based grid disk is using flash which also for flash cache
C is right. smart flash cache is extension of SGA and single block will speed up access because it won’t need to go to physical disk
D is wrong. flash based grid disk is no difference than hard-disk based grid disk. So smart scan may not always true
E is right. smart flash cache is extension of SGA and single block will speed up access because it won’t need to go to physical disk
F is right. smart flash log is using the same flash as flash cache
So B.C.E.F. are correct
BCEF correct as L. Zhu once more explained in great detail. One more point: AD wrong. very ofter special words like ‘ALWAYS’ or ‘NEVER’ will gibe you a hint, that this answer is probably wrong. The point is here that these types of words are excluding or including everything which is most of the time not the case. Other special words are for example: ‘AUTOMATICALLY’ or ‘EXACTLY’.