You recently upgraded your Exadata image to the latest release; previously you were using
11.2.0.3.
At the same time, you decide to address some performance problems as follows:
You noticed increased latency for the database log writer, especially during the quarterly battery
learn cycle on the cells.
You have complaints of erratic performance from certain write-intensive applications.
Which two actions could improve performance in these areas?
A.
Enable write-back flashcache by setting lunWriteCacheMode to Write Back Mode.
B.
Use ALTER TABLE in the database to set CELL_FLASH_CACHE = KEEP for the tables
belonging to the affected application.
C.
Configure Smart Flash Log on the cells to use some of these of the space on the cell flash
devices.
D.
Configure the table belonging to the affected application using CELLCLI, to the set
CELL_FLASH_CACHE = KEEP.
E.
Configure Smart Flash Log on the database server to use server flash memory.
Explanation:
B: The following command could be used to pin the table CUSTOMERS in Exadata
Smart Flash Cache
ALTER TABLE customers STORAGE (CELL_FLASH_CACHE KEEP)
C:Creating Flash Disks Out Of The Flash Cache
When an Exadata cell is installed, by default, all the flash is assigned to be used as flash cache
and
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.Note:
*Pinning Objects In The Flash Cache
Preferential treatment over which database objects are cached is also provided with the Exadata
Smart Flash Cache. For example, objects can be pinned in the cache and always be cached, or
an
object can be identified as one which should never be cached. This control is provided by the
new storage clause attribute, CELL_FLASH_CACHE, which can be assigned to a database table,
index, partition and LOB column
*There are two techniques provided to manually use and manage the cache. The first enables the
pinning of objects in the flash cache. The second supports the creation of logical disks out of the
flash for the permanent placement of objects on flash disks.
I think answers should be A & C.
Write back was introduced in the 11.2.3.1 version, so A is not true
b & e are correct, so easy
A & B seems like correct answer.
A is correct becauase you are upgrading to latest release from 11.2.0.3
A, B
I think it should be B, C. Because SFL was introduced in 11.2.2.4.2.
a and c
the 027 is now x3 and x4
I agree. A C
B & C are the correct answers.
Not A: there is no lunWriteCacheMode attribute, the correct attribute is flashCacheMode.
There is “lunWriteCacheMode”
http://www.oracle.com/technetwork/articles/oem/exadata-commands-part3-402445.html
CellCLI> list lun detail
name: 0_0
cellDisk: CD_00_cell01
deviceName: /dev/sda
diskType: HardDisk
id: 0_0
isSystemLun: TRUE
lunAutoCreate: FALSE
lunSize: 557.861328125G
lunUID: 0_0
physicalDrives: 34:0
raidLevel: 0
lunWriteCacheMode: “WriteBack, ReadAheadNone, Direct, No Write Cache if Bad BBU”
status: normal
name: 0_1
cellDisk: CD_01_cell01
… output truncated …
Thanks for the correction. I will go with A & C
B and C are the correct answer.A -there is no way or command to set.it is by default
A is wrong. writeback is set to flashcachemode, not lunWriteCacheMode
B is right. CELL_FLASH_CACHE is for exadata storage
C is right. SFL is good for write intensive logwriter
D is wrong. CELL_FLASH_CACHE is not set from cellcli
E is wrong. SFL is not set from database server.
so B.C. are right.
BC pefect explantier from L. Zhu
B: Use ALTER TABLE in the database to set CELL_FLASH_CACHE = KEEP for the tables belonging to the affected application
C: Configure Smart Flash Log on the cells to use some of these of the space on the cell flash devices
Explanation:
Pin tables that makes a lot of I/O using alter table cell_flash_cache=keep
The Smart Flash Log needs to be configured on cells that will use space of the cell flash disks
Option A stated as “Enable write-back flashcache” in the exam.