Oracle Oracle Certifications 1Z0-070 Questions & Answers

• Question 81:

  Which two statements are true about RMAN incremental level-1 backups for a database running on an X5 Database Machine?

  A. Block Change tracking (BCT) is not needed for databases in an X5 Database Machine, because ASM automatically does block change tracking when diskgroups are built from griddisks.

  B. cellsrv filters blocks and returns only those that have changed since the last backup, for databases in archivelogmode.

  C. cellsrv returns all blocks that have been or might have been changed since the last backup, and RMAN filters the blocks that do not require backup.

  D. cellsrv filters blocks and returns only those that have changed since the last backup, for databases in noarchivelogmode.

  E. Block Change Tracking (BCT) is not needed for databases in an X5 Database Machine, because change tracking is done by cellsrv.

  Correct Answer: DE

  Explanation:

  D: Whenever data blocks change, the Change Tracking Writer (CTWR) background process tracks the changed blocks in a private area of memory.

  When RMAN performs an incremental backup on the Exadata platform, cellsrv filters out unwanted blocks and sends back only those that have changed since the last level 0 or level 1 backup.

  E: For the Exadata platform, you may choose to allow cellserv to do all the blocking filtering for incremental backups.

  Note: RMAN block change tracking is used to improve the performance of incremental backup. The level 0 incremental backup scans the entire database but level 1 incremental backups use the block change tracking file to scan only the blocks that have changed since the last backup. This significantly reduces the amount of reads that are required on the database.

  References: Expert Oracle Exadata (29 Aug 2015), page 319

• Question 82:

  Which components of an Exadata storage server image, if updated, may require that a patch also be applied to the database servers in an Exadata X6 Database Machine?

  A. Linux operating system on the storage server

  B. InfiniBand HCA firmware on the storage server

  C. Storage server hard disk device drivers

  D. Storage server flash device drivers

  Correct Answer: D

  Explanation:

  patches are intended for and include fixes for both the storage servers and Compute servers, and optionally InfiniBand switches.

  Patching order You should patch the Exadata Database Machines in the following sequence

  1.

  Oracle GI/RDBMS Homes

  2.

  Exadata Storage Cells

  3.

  Compute nodes

  4.

  Infiniband Switches

  References: https://www.toadworld.com/platforms/oracle/w/wiki/11640.oracle-exadata-patching

• Question 83:

  Which two statements are true about the use of DBFS, ACFS, and external file systems and components in an X5 Database Machine environment?

  A. ACFS uses storage in a database on the database machine

  B. DBFS supports file system snapshots.

  C. ACFS supports file system snapshots.

  D. Storage Area Network (SAN) –based file systems may be accessed directly from the storage servers in a database machine.

  E. Oracle Sun ZFS Storage Appliance-based files are not automatically protected by Data Guard.

  Correct Answer: BC

  Explanation:

  DBFS SecureFiles Store Capabilities include support for file system snapshots.

  Oracle ACFS includes advanced features such as file system snapshot.

  References:

  http://www.oracle.com/technetwork/ru/database/dbfs-sf-oow2009-v2-160969.pdf

  http://www.oracle.com/technetwork/database/database-technologies/cloud-storage/benefits-of-oracle-acfs2379064.pdf

• Question 84:

  Which two are true about sparse griddisks and their use in disk groups on an X5 Exadata Database Machine?

  A. Sparse diskgroups must be created using sparse griddisks.

  B. Sparse diskgroups may be created using a combination of sparse and non-sparse griddisks.

  C. Sparse diskgroups may not be used for database snapshots.

  D. Additional space for a sparse griddisk is allocated as soon as newly written data is stored in the flashcache on a cell.

  E. The virtual size of a sparse griddisk may exceed the physical size of the space occupied by the griddisk.

  Correct Answer: AE

  Explanation:

  A: A sparse ASM disk group is composed of sparse grid disks.

  E: Sparse grid disks allocate space as new data is written to the disk, and therefore have a virtual size that can be much larger than the actual physical size. Sparse grid disks can be used to create a sparse disk group to store database files that will use a small portion of their allocated space. Sparse disk groups are especially useful for quickly and efficiently creating database snapshots on Oracle Exadata. Traditional databases can also be created using a sparse disk group.

  References:

  http://docs.oracle.com/cd/E80920_01/SAGUG/exadata-storage-server-snapshots.htm#SAGUG-GUID42945059-13FD-4F6A-B7FA-A1201D16238F http://docs.oracle.com/cd/E80920_01/DBMSO/exadata-whatsnew.htm#DBMSO22120

• Question 85:

  You wish to determine if the I/O resource management plan that you created has helped improve the performance of OLTP category I/Os on your X6 Exadata Database Machine.

  You decide to examine the relevant metrics on all the cells, to see whether the I/O rate has improved for this category compared to last week, and whether waits and wait time have been reduced.

  You issue this command on the first cell:

  

  You examine the output from the first cell which contains:

  

  Which two sets of metrics would you use to determine whether the I/O performance has improved for the OLTP category for the duration of the one-hour measurement period?

  A. CT_IO_RQ_SM, CT_IO_RQ_LG, CT_IO_RQ_SM_SEC, and CT_IO_RQ_LG_SEC

  B. CT_IO_UTIL_SM and CT_IO_UTIL_LG

  C. CT_IO_RQ_SM_SEC and CT_IO_RQ_LG_SEC D. CT_IO_WT_SM, CT_IO_WT_LG, CT_IO_WT_SM_RQ, and CT_IO_WT_LG_RQ

  Correct Answer: D

  Explanation: CT_IO_RQ_SM The cumulative number of small I/O requests issued by the category for hard disks. A large value indicates a heavy I/O workload from this category. CT_IO_RQ_LG The cumulative number of large I/O requests issued by the category for hard disks. A large value indicates a heavy I/O workload from this category. CT_IO_WT_SM_RQ The average IORM wait time per request for small I/O requests issued to hard disks by an IORM category. CT_IO_WT_LG_RQ The average IORM wait time per request for large I/O requests issued to hard disks by an IORM category.

  Incorrect Answers:

  A: CT_IO_RQ_SM_SEC

  This metric is derived from CT_IO_RQ_SM. It specifies the rate of small I/O requests issued by the

  category for hard disks. Its units are number of I/O requests per second. A large value indicates a heavy I/

  O workload from this category in the past minute.

  B: CT_IO_UTIL_SM

  The percentage of disk resources utilized by small requests from this category.

  References: http://docs.oracle.com/cd/E80920_01/SAGUG/exadata-storage-server-monitoring.htm

• Question 86:

  Which three are true about Exadata Smart Flash Log?

  A. Databases on the Database Machine use Exadata Smart Flash Log by default.

  B. I/O Resource Manager database plans can be used to enable or disable Exadata Smart Flash Log for individual databases.

  C. LGWR will not wait for writes to Exadata Smart Flash Log if the write to a disk-based logfile completes first.

  D. I/O Resource Manager category plans can be used to enable or disable Exadata Smart Flash Log for different I/O categories.

  E. The use of Exadata Smart Flash Logs is mandatory for support of production databases.

  Correct Answer: ABC

  Explanation:

  A: Exadata I/O Resource Manager (IORM) has been enhanced to enable or disable Smart Flash Logging for the different databases running on the Database Machine, reserving flash for the most performance critical databases.

  B: The Exadata I/O Resource Manager (IORM) has been enhanced to enable or disable Smart Flash Logging for the different databases running on the Database Machine.

  C: Smart Flash Logging works as follows. When receiving a redo log write request, Exadata will do parallel writes to the on-disk redo logs as well as a small amount of space reserved in the flash hardware. When either of these writes has successfully completed the database will be immediately notified of completion. If the disk drives hosting the logs experience slow response times, then the Exadata Smart Flash Cache will provide a faster log write response time. Conversely, if the Exadata Smart Flash Cache is temporarily experiencing slow response times (e.g., due to wear leveling algorithms), then the disk drive will provide a faster response time. This algorithm will significantly smooth out redo write response times and provide overall better database performance.

  Incorrect Answers:

  D: Category plans are configured and enabled using the CellCLI utility on the cell. Only one category plan can be enabled at a time.

  References: http://structureddata.org/2011/10/12/exadata-smart-flash-logging-explained/

• Question 87:

  Which two are true concerning Columnar Flash Caching?

  A. It can be enabled or disabled for individual databases by using I/O Resource Manager database plans.

  B. It automatically transforms ROW STORE COMPRESS compressed data into a pure columnar format during Exadata Smart Flash Cache population.

  C. Data is either cached in Hybrid Columnar Compressed format or in pure compressed format, but never in both formats at the same time.

  D. It is enabled by default.

  E. It automatically transforms Hybrid Columnar Compressed (HCC) data into a pure columnar format during Exadata Smart Flash Cache population.

  F. It improves single-row lookup performance.

  Correct Answer: DE

  Explanation:

  D: In-Memory Columnar Caching on cells is enabled by default when the INMEMORY_SIZE is configured. You do not need to do anything to get this enhancement.

  E: Columnar Flash Caching implements a dual format architecture in Exadata flash by automatically transforming frequently scanned Hybrid Columnar Compressed data into a pure columnar format as it is loaded into the flash cache.

  Incorrect Answers:

  F: Columnar Flash Caching accelerates reporting and analytic queries while maintaining excellent performance for OLTP style single row lookups.

  References:

  http://docs.oracle.com/cd/E80920_01/SAGUG/exadata-storage-server-monitoring.htm#SAGUG20883 http://www.oracle.com/technetwork/database/exadata/exadata-x5-8-ds-2745934.pdf

• Question 88:

  You are evaluating the performance of a SQL statement that accesses a very large table. You run this query:

  

  Identify two reasons why the “cell physical IO interconnect bytes” statistic is greater than the “cell physical IO interconnect bytes returned by smart scan” statistic.

  A. There is a transaction, which committed after the query began, that has modified some of the table blocks, causing some “cell single block physical reads”to be requested by the database instance, resulting in additional I/O.

  B. There are chained rowsin the table, causing some “cell single block physical reads”to be requested by the database instance, resulting in additional I/O.

  C. The table is a hash clustered table, causing “cell multiblock physical reads”to be requested by the database instance, resulting in additional I/O.

  D. The table is list partitioned, causing “cell list of blocks physical reads”to be requested by the database instance, resulting in additional I/O.

  E. There is a local index ona list partitioned tableon the column used in the WHERE clause, causing “cell list of blocks physical reads”to be requested by the database instance, resulting in additional I/O.

  Correct Answer: CD

  Explanation:

  C: Scan on a clustered table can prevent a Smart Scan from occur.

  D: Scan on an index-organized table can prevent a Smart Scan from occur.

  Note: The Cell physical IO interconnect bytes returned by smart scan metric shows how many bytes of I/O

  were returned by a smart scan to the database server.

  References: https://uhesse.com/2011/01/19/exadata-part-i-smart-scan/

• Question 89:

  Which two completely prevent a Smart Scan from occurring?

  A. querying a table containing many chained rows

  B. querying a table containing many migrated rows

  C. performing a minimum or maximum function on an indexed column

  D. performing a Fast Full Index scan on a reverse key index

  E. referencing more than 255 columns form an OLTP compressed table in a query

  F. querying a table containing a JSON column

  Correct Answer: BE

  Explanation:

  B: Migrated Rows is a special case of chained rows. Migrated rows still affect performance, as they do in conventional storage situations, but with the additional overhead of reducing the beneficial effects of “Smart Scan” in addition to increasing the number of I/Os

  E: Smart Scans - broadly speaking and ignoring edge cases - can only transport a maximum of 254 columns from a single (non-HCC) segment. Requesting more columns will simply disable Smart Scans for that segment.

  An interesting limitation to Exadata Smart Scans - if more than 254 columns from a table (not HCC compressed, more on that in moment) need to be projected, Smart Scans for that particular segment will be disabled and Exadata will fall back to conventional I/O. This means that the number of columns in the projection clause can make a significant difference to performance, since only Smart Scans allow taking advantage of offloading and particularly avoiding I/O via Storage Indexes.

  Incorrect Answers:

  A: Smart scan can cope with some cases of chained rows

  References: http://oracle-randolf.blogspot.se/2013/01/exadata-smart-scan-projection-limitation.html

• Question 90:

  Which statement is true about operating systems in an X5 Database Machine multirack configuration consisting of two full racks and one Exadata storage expansion rack?

  A. All Exadata storage servers used by the same virtual cluster nodes must run the same O/S but Exadata Storage Servers in different clusters may run different operating systems.

  B. All Exadata storage servers must run the Oracle Solaris O/S and all database servers within the same cluster must run Oracle Linux.

  C. All Exadata storage servers may run Oracle Virtual Machine (OVM).

  D. All Exadata storage servers must run Oracle Linux.

  E. All Exadata storage servers must run the Oracle Linux O/S and all database servers within the same cluster must run the same version of Oracle Virtual Machine (OVM).

  Correct Answer: D

  Explanation:

  On both physical and virtual deployments, Exadata systems use minimal Linux distributions to ensure that

  just the RPMs needed to run Oracle database, are installed and enabled.

  References: http://www.oracle.com/technetwork/database/exadata/exadata-x5-2-ds-2406241.pdf