Oracle 1z0-027 Exam Practice Questions (P. 3)
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Question #11
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.
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.
- AIdentify the griddisk located on the poorly performing flashdisk and drop it from the associated ASm diskgroup.
- BVerify that the griddisk located on the poorly performing flashdisk has been successfully dropped from the associated ASM diskgroup.
- CDrop the flashcache on all cell.
- DSafely power off the cell containing the poorly-performing flashdisk.
- EReplace the poorly performing flashdisk.
- FPower up the cell containing the replaced flashdisk and activate all griddisks.
- GRecreate the flashcache on the cell using all flashdisks.
- HCreate a new griddisk on the replaced flashdisk.
- IAdd the griddisk back into the ASM diskgroup to which it belonged.
Correct Answer:
ADEFHI
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
ADEFHI
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
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Question #12
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?
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?
- AEnable write-back flashcache by setting lunWriteCacheMode to Write Back Mode.
- BUse ALTER TABLE in the database to set CELL_FLASH_CACHE = KEEP for the tables belonging to the affected application.
- CConfigure Smart Flash Log on the cells to use some of these of the space on the cell flash devices.
- DConfigure the table belonging to the affected application using CELLCLI, to the set CELL_FLASH_CACHE = KEEP.
- EConfigure Smart Flash Log on the database server to use server flash memory. BC
Correct Answer:
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.
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.
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Question #13
Which two statements are true about the use of direct path loads when selecting from external tables in a database on a Database Machine?
- AINSERT INTO . . . SELECT FROM statements, executed serially, which select from external tables, require the APPEND hint to use direct path loading.
- BCREATE TABLE . . . AS SELECT statements, which select from external tables, attempt to use in direct path loading automatically.
- CCREATE TABLE . . . AS SELECT statements, which select from external tables, require the APPEND hint to use direct path loading.
- DINSERT INTO . . . SELECT FROM statements, executed serially, which select from external tables, are unable to use direct path loading.
Correct Answer:
AB
A CTAS (Create table as select) will always use direct path (B, not C) load but IAS (Insert as select) statement will not. In order to achieve direct path load with an
IAS statement you must add the APPEND hint to the command (A, not D).
Direct path loads can also run in parallel. You can set the parallel degree for a direct path load either by adding the PARALLEL hint to the CTAS or IAS statement or by setting the PARALLEL clause on both the external table and the table into which the data will be loaded.
Once the parallel degree has been set at CTAS will automatically do direct path load in parallel but an IAS will not. In order to enable an IAS to do direct path load in parallel you must alter the session to enable parallel DML.
Note:
* Parallel Direct Path Load
The key to good load performance is to use direct path loads wherever possible. A direct path load parses the input data according to the description given in the external table definition, converts the data for each input field to its corresponding Oracle data type, then builds a column array structure for the data. These column array structures are used to format Oracle data blocks and build index keys. The newly formatted database blocks are then written directly to the database, bypassing the standard SQL processing engine and the database buffer cache.
Reference: Best Practices for Implementing a Data Warehouse on the Oracle Exadata Database Machine; Using CTAS & Exchange Partition Replace IAS for
Copying Partition on Exadata
AB
A CTAS (Create table as select) will always use direct path (B, not C) load but IAS (Insert as select) statement will not. In order to achieve direct path load with an
IAS statement you must add the APPEND hint to the command (A, not D).
Direct path loads can also run in parallel. You can set the parallel degree for a direct path load either by adding the PARALLEL hint to the CTAS or IAS statement or by setting the PARALLEL clause on both the external table and the table into which the data will be loaded.
Once the parallel degree has been set at CTAS will automatically do direct path load in parallel but an IAS will not. In order to enable an IAS to do direct path load in parallel you must alter the session to enable parallel DML.
Note:
* Parallel Direct Path Load
The key to good load performance is to use direct path loads wherever possible. A direct path load parses the input data according to the description given in the external table definition, converts the data for each input field to its corresponding Oracle data type, then builds a column array structure for the data. These column array structures are used to format Oracle data blocks and build index keys. The newly formatted database blocks are then written directly to the database, bypassing the standard SQL processing engine and the database buffer cache.
Reference: Best Practices for Implementing a Data Warehouse on the Oracle Exadata Database Machine; Using CTAS & Exchange Partition Replace IAS for
Copying Partition on Exadata
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Question #14
Your customer wants you to partition the database and storage grids in his X3-2 full rack, creating database clusters and two storage grids.
One cluster will be used for production and should consist of 6 databases servers and 11 cells from the first storage grid.
The other cluster will be used for test and development, and should consist of 2 database servers and 3 cells from the second storage grid.
The storage must be partitioned so that the cells are visible only to the appropriate database servers based on the description above.
What must be done to achieve this?
One cluster will be used for production and should consist of 6 databases servers and 11 cells from the first storage grid.
The other cluster will be used for test and development, and should consist of 2 database servers and 3 cells from the second storage grid.
The storage must be partitioned so that the cells are visible only to the appropriate database servers based on the description above.
What must be done to achieve this?
- AConfigure Exadata realms using Oracle ASM scoped security mode.
- BConfigure Exadata realms using Database scoped security mode.
- CEdit the CELLIP.ORA file on each database server to contain IP addresses of cells in the storage grid associated with cluster to which that database server belongs.
- DEdit the CELLINIT.ORA file on each database server to contain IP addresses of cells in the storage grid associated with the cluster to which that database server belongs.
- EEdit the CELLIP.ORA file on each database server to contain IP addresses of database servers which are allowed access to specific cells in the same storage grid.
- FEdit the CELLIP.ORA file on each cell to contain IP addresses of database servers in the database server grid that are associated with the storage grid to which that cell belongs.
Correct Answer:
C
cellip.ora
The cellip.ora is the configuration file, on every compute node, that tells ASM instances which cells are available to this cluster.
Here is a content of a typical cellip.ora file for a quarter rack system:
$ cat /etc/oracle/cell/network-config/cellip.ora
cell="192.168.10.3"
cell="192.168.10.4"
cell="192.168.10.5"
Now that we see what is in the cellip.ora, the grid disk path, in the examples above, should make more sense.
Note:
* cellinit.ora decides which network takes storage traffic.
* cellip.ora - list of cells, new cells can be added dynamically without shutdown
C
cellip.ora
The cellip.ora is the configuration file, on every compute node, that tells ASM instances which cells are available to this cluster.
Here is a content of a typical cellip.ora file for a quarter rack system:
$ cat /etc/oracle/cell/network-config/cellip.ora
cell="192.168.10.3"
cell="192.168.10.4"
cell="192.168.10.5"
Now that we see what is in the cellip.ora, the grid disk path, in the examples above, should make more sense.
Note:
* cellinit.ora decides which network takes storage traffic.
* cellip.ora - list of cells, new cells can be added dynamically without shutdown
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Question #15
Which three statements are true about the initial storage configuration after the standard deployment of a new database Machine?
- AThe Data_<DBM_Name> and RECO_<DBM_Name> ASM diskgroups are built on part of the interleaved griddisks.
- BThe Data_<DBM_Name> and RECO_<DBM_Name> ASM diskgroups are built on top of the non-interleaved griddisks.
- CThere is a free space available on the hard disks inside the database servers for possible extension of the /u01 file system.
- DThere is no free disk space available on the hard disk inside the database servers for possible extensions of the /u01 file system.
- EThere is free space available on the flashdisk inside the Exadata storage servers for possible use as flash-based griddisks.
- FThere is no free disk available on the flashdisk inside the Exadata storage servers for possible use as flash-based griddisks.
Correct Answer:
BCF
B( not A): Griddisks are the fourth layer of abstraction, and they will be the Candidate Disks to build your ASM diskgroups from. By default (interleaving=none on the Celldisk layer), the first Griddisk that is created upon a Celldisk is placed on the outer sectors of the underlying Harddisk. It will have the best performance therefore. If we follow the recommendations, we will create 3 Diskgroups upon our Griddisks: DATA, RECO and SYSTEMDG.
Note:
* non-root partition (/u01).
* Oracle Database files: DATA disk group.
* Flashback log files, archived redo files, and backup files: RECO disk group.
BCF
B( not A): Griddisks are the fourth layer of abstraction, and they will be the Candidate Disks to build your ASM diskgroups from. By default (interleaving=none on the Celldisk layer), the first Griddisk that is created upon a Celldisk is placed on the outer sectors of the underlying Harddisk. It will have the best performance therefore. If we follow the recommendations, we will create 3 Diskgroups upon our Griddisks: DATA, RECO and SYSTEMDG.
Note:
* non-root partition (/u01).
* Oracle Database files: DATA disk group.
* Flashback log files, archived redo files, and backup files: RECO disk group.
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