Yesterday, an Exadata storage server flashdisk entered the poor performance state.
This flashdisk os used by flashcache and has a griddisk which is a member of a normal
redundancy diskgroup.
Identify the six steps you must perform to replace flashdisk.
A.
Identify the griddisk located on the poorly performing flashdisk and drop it from the associated
ASm diskgroup.
B.
Verify that the griddisk located on the poorly performing flashdisk has been successfully
dropped from the associated ASM diskgroup.
C.
Drop the flashcache on all cell.
D.
Safely power off the cell containing the poorly-performing flashdisk.
E.
Replace the poorly performing flashdisk.
F.
Power up the cell containing the replaced flashdisk and activate all griddisks.
G.
Recreate the flashcache on the cell using all flashdisks.
H.
Create a new griddisk on the replaced flashdisk.
I.
Add the griddisk back into the ASM diskgroup to which it belonged.
Explanation:
Note:
*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
I think correct answer should be A B D E F G
http://docs.oracle.com/cd/E50790_01/doc/doc.121/e51951/storage.htm#DBMMN22021
I’m thinking of A D E F G H
Not B but H
Checked the doc again, for bad performance, need to drop and recreate flashcache
so C & G should be in
A C D E F G
A is right. Since it is poorly performed, you have to identify and drop from ASM
B is wrong. there is no error, so system won’t detect and drop for you
C is wrong. You do not need to drop flashcache on itself and other cell nodes.
D is right. changing flashcache requires power off the cell node.
E is right.
F is right. You need to activate griddisk because you safely power off the cell.
G is wrong. you do not need to recreate flashcache
H is right. griddisk on flashcache needs to be re-created.
I is right. you need to add this griddisk back into ASM since you dropped it from ASM
So A.D.E.F.H.I. are the correct answer.
https://docs.oracle.com/cd/E50790_01/doc/doc.121/e51951/storage.htm#DBMMN21127
A, D, E, F, C, G
I Read the document and found that the correct answer is
A (Correct – as you have to identify the grid disk and drop it from the ASM disk group
B (Correct – I don’t know why all of you removed option B which is verifying that the grid disk is successfully removed. the document clearly mentioned that It is possible that the DROP command with the FORCE option could fail due to offline partners. So verifying is mandatory and B is correct)..
C (not correct – No Need to Drop the flash cache now as we are going to shutdown the cell and recreate the flash cache after replacing the card … So G covers C already)
D + E + F (Correct – 100 % and all agree as they include shutdown – replace -startup)
G (Correct – as you need to recreate the flache disk , drop and create it again with all disks)
H (Wrong – the grid disk will be recreate automatically after starting up the cell with the new replaced disk.
I (Wrong – the grid disk will be automatically join the asm diskgroup)
correct answer is: A B D E F G
See the reference https://docs.oracle.com/cd/E50790_01/doc/doc.121/e51951/storage.htm#DBMMN21127
Answer must be ABDEFI.
A-> right
B-> need to verify if disk is dropped. rebalnce must be finished.
C->happens automatically WRONG
D,E,F -> no explanation required.
H-> Ideally griddisk creation is automatic process so it is WRONG.
I -> need to add back to ASM diskgroup as we had dropped it.
This case is clearly documented. Hisham is rightly written above.
https://docs.oracle.com/cd/E50790_01/doc/doc.121/e51951/storage.htm#DBMMN21127
Correct answer is: A B D E F G
11.2.3.2 onwards such under pinning disks, when entering into “Poor Performance” state, will automatically be dropped from ASM diskgroup and be dissabled on flashdisk. Hence answer should be as below,
A (Incorrect): Due to fact as above mentioned.
B (Correct): Need to be sure automatic drop of griddisk on poorly performing physical disk is performed succesfully.
C (Incorrect): No need to drop flash cache on all cells. Flash disk pertaining to poor performance is automatically done.
D (Correct): Shut down perticular cell, since flash cards are not hot swapable.
E (Correct): Replace the affected flash disk.
F (Correct): Porwer up and activate activate griddisks.
G (Incorrect): No need to perform this activity.
H (Correct): Create new grid disk on replaced flash disk.
I (Correct): Add grid disk into original diskgroup.
Hence correct answer sequence is: B,D,E,F,H,I
Correct Ans: B,D,E,F,C,G
Removing Flash Disk Due to Bad Performance
A single bad flash disk can degrade the perf
ormance of other good
flash disks. It is
better to remove the bad flash disk from the
system than let it remain. Starting with
release 11.2.3.2, an underperforming disk is automatically identified and removed
from active configuration.
Oracle Exadata Database Machine then runs a set of
performance tests.
1.
If the flash disk is used for flash cache, th
en disable flash cache that is part of the
flash disk using the following commands:
CellCLI > ALTER FLASHCACHE … FLUSH
CellCLI > DROP FLASHCACHE
CellCLI > CREATE FLASHCACHE CELLDISK=’fd1,fd2,fd3,fd4
2.
If the flash disk is used for grid disks, then use the following command to direct
Oracle ASM to stop using the bad disk at once:
SQL> ALTER DISKGROUP diskgroup_name DROP DISK asm_disk_name FORCE
3.
Shut down the cell
4.
Remove the bad flash disk, and re
place it with a new flash disk.
5.
Power up the cell. The cell services are st
arted automatically. As part of the cell
startup, all grid disks are automatically
ONLINE
in Oracle ASM.
6.
Add the new flash disk to flash
cache using the following commands:
CellCLI> DROP FLASHCACHE
CellCLI> CREATE FLASHCACHE ALL
7.
Verify that all grid disks have been successfully put online using the following
command:
CellCLI> LIST GRIDDISK ATTRIBUTES asmmodestatus
Removing Flash Disk Due to Bad Performance
https://docs.oracle.com/cd/E50790_01/doc/doc.121/e51951/storage.htm#DBMMN21127
A: CORRECT – you need to drop the disk from diskgroup
B: CORRECT – you need to wait for rebalance complete
C: WRONG – you don’t need to drop the flashcache because the flashdisk is used by ASM Diskgroup
D: CORRECT – power off cell
E: CORRECT – replace the disk
F: CORRECT – power on cell
G: WRONG – you don’t need to recreate the flashcache , this disk will be used by ASM Diskgroup
H: WRONG – the disk is recreated as a griddisk automatically by cell
I: CORRECT – you need to return the disk to ASM diskgroup
http://docs.oracle.com/cd/E50790_01/doc/doc.121/e51951/storage.htm#DBMMN21904
ANSWER IS :- B D E F C G