Oracle 1Z0-027 Online Practice Questions and Exam Preparation

Oracle 1Z0-027 Online Questions & Answers

• Question 21:

  You plan to migrate an Oracle database that supports an online transaction processing (OLTP) workload to your Database Machine.

  Following are details for the source database:

  Database version: 10.2.0

  Byte order: Big Endian HP-UX (64-bit)

  Database size: 24 TB

  Storage: ASM with 1 MB allocation unit size

  Which two are supported migration methods?

  A. Physical migration using ASM online Migration
  B. Physical migration using Transportable Database
  C. Logical migration using Oracle Streams
  D. Local migration using Oracle Streams
  E. Logical migration using logical standby
  B. Physical migration using Transportable Database
  C. Logical migration using Oracle Streams

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  Note:

  * physical migration techniques (e.g. Data Guard Physical Standby, Transportable Database, Transportable Tablespaces(B), Rapid Clone) vs. logical migration techniques(C)(e.g. Oracle Data Pump).

  *You can use either Data Pump export/import or original export/import for Streams instantiations.

  *The Oracle Exadata Database Machine runs the standard Oracle Database. Therefore, any application that runs with the Oracle Database today can be seamlessly migrated to the Exadata Database Machine with no changes to the application.

  *There are several techniques for migrating data to a Database Machine. Migration can be done using Oracle Recovery Manager (RMAN) to backup from traditional storage and restore the data onto Exadata. Oracle Data Guard can also be used to facilitate a migration. This is done by first creating a standby database based on Exadata storage. The standby can be using Exadata storage and the production database can be on traditional storage. By executing a fast switchover, taking just seconds, you can transform the standby database into the production database. This provides a built-in safety net as you can undo the migration very gracefully if unforeseen issues arise. Transportable Tablespaces(B)and Data Pump may also be used to migrate to Exadata. Any technique used to move data between Oracle Databases can be used with Exadata.

• Question 22:

  You are examiningthe existingIORM configurationon the cells of Database Machine, to see if they require mymodifications based on recent changesto variousworkloads. All seven cellsin your X3-2 half-rackshown thefollowing:

  

  Which two are true about I/O to the cells using this plan?

  A. I/O requests in the batch category may use flashcache if the I/O is from the sales finance database, and these I/O requests are guaranteed to get 80% of the I/O if the interactive category I/Os use no more than 20%.
  B. I/O requests made by sessions in the marketing database may use flashing and flashcache if no other categories or database or database are using flashing and flashcache at the same time.
  C. I/O requested in the interactive category may use flashdns if the I/O is from the sales or finance databases, and these I/O requests are guaranteed to get 90% of the I/O if the enough I/Os are issued in this category.
  D. I/O requests from the sales database may use flashing regardless of the I/O category.
  E. No I/Os in any category or from any database may use flashing or flashcache because the objective is off.
  D. I/O requests from the sales database may use flashing regardless of the I/O category.
  E. No I/Os in any category or from any database may use flashing or flashcache because the objective is off.

  ---

  list iormplan detail

  Note:

  *The I/O Resource Manager (IORM) extends the concept of resource groups with a new attribute known as a category. While resource groups allow DBRM to manage resources within a a database, categories provide I/O resource

  management among multiple databases.

  *cellcli> alter iormplan objective='balanced'

  -- {balanced | off | low_latency | high_throughput | auto

  "off" simply turns off the IORM plan's IO metering.

• Question 23:

  Your database Machine has the exachk utility pre-installed and you decide to use it periodically, to validate the installation against Oracle's recommended best practices. Which two actions could you take to do this?

  A. Use a cron job on a database node to run it at regular intervals.
  B. Rut it once from a database node and it will then perform periodic monitoring automatically.
  C. Use a cron job on each cell to run it at regular intervals.
  D. Run it once on each cell and it will then perform periodic monitoring automatically.
  E. Create a Job in Enterprise Manager to run the exachk utility at regular intervals.
  B. Rut it once from a database node and it will then perform periodic monitoring automatically.
  E. Create a Job in Enterprise Manager to run the exachk utility at regular intervals.

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  Note:

  *Oracle Exadata Database Machine Cells are added as targets during the database machine discovery workflow and are grouped automatically under the group Exadata Grid.

  Based on the Exadata Grid group, a group of Exadata cells can be managed together through Enterprise Manager Cloud Control 12c.

• Question 24:

  Which statement is true about operating systems on database Machine multi-rack configuration consisting of two full racks and one Exadata storage rack?

  A. All Exadata storage servers and all database servers must run the Oracle Linux O/S and X3-8 database server may run the Oracle Solaris O/S.
  B. All Exadata storage servers must run the Oracle Linux O/S and all database servers within the same cluster must run the Oracle Linux O/s.
  C. All Exadata storage servers must run the OracleLinuxO/S and all database servers within the same cluster must run the same O/s.
  D. All Exadata Storage Servers must run the Oracle Solaris O/S and all database servers within the same cluster must run the same O/S.
  E. All Exadata storage servers in the same cluster must run the same O/S but Exadata Storage Servers in different clusters may run a different O/S.
  D. All Exadata Storage Servers must run the Oracle Solaris O/S and all database servers within the same cluster must run the same O/S.

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  Note:

  *Oracle Linux or Solaris based database server

• Question 25:

  Which three are true about Smart Flash log?

  A. I/O Resource Manager database plans can be used to enable or disable Smart Flash Log for different databases.
  B. LGWR will not wait for writes to Smart Flash log if the write to a disk based logfile completes first.
  C. Smart Flash Log is enabled by default, using 1024 MB of Rash storage on each storage server.
  D. You can remove Smart Flash Log from a single storage server with the drop flashing command.
  E. I/O Manager category plans can be used to enable or disable Smart Flash LogFor different I/O categories.
  A. I/O Resource Manager database plans can be used to enable or disable Smart Flash Log for different databases.
  B. LGWR will not wait for writes to Smart Flash log if the write to a disk based logfile completes first.
  D. You can remove Smart Flash Log from a single storage server with the drop flashing command.

  ---

  A: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.

  B: 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.

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

  Incorrect:

  Not C:By default, 512 MB of the Exadata flash is allocated to Smart Flash Logging

• Question 26:

  You are monitoringand evaluatinga create index statement on yourDatabaseMachine and haverun the followingqueryafterexecutingstatement, providing the output. Shown:

  

  Select two reasons why the statement would have produced so many "cell single block physical read" waits compared to "cell smart table scan"waits.

  A. There are huge numbers of migrated rows in the table on which the index is being built.
  B. There is an uncommitted transaction that has modified one block of the table on which the index is being built, in each cell.
  C. Thereis a transaction that has modified one block of the table on which the index is being built in each cell, which committed after the create index began.
  D. There are huge numbers of chained rows in the table on which the index is being built.
  E. There is a ROWID column in the table on which the index is being built.
  A. There are huge numbers of migrated rows in the table on which the index is being built.
  D. There are huge numbers of chained rows in the table on which the index is being built.

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  A:It could be that row migration.

  D:It could be that row migration or chained rows could cause it.

  Note:

  *Some facts about scans:

  Scans exists in "OLTP" systems

  Exadata smart scan requires a direct path read.

  A direct path read is chosen at runtime based on internal heuristics The STORAGE clause in an explain plan doesnt necessarily mean you will perform a smart scan.

  *The buffer caching in certain "OLTP" environments can occasionally induce conventional reads when smart scan is faster.

  *Typically see cell multiblock physical read instead of cell smart table scan waits

  *No one-size-fits-all solution can be given here but it is very fixable.

• Question 27:

  Identify two valid reasons for creating multiple griddisks on a Single celldisk.

  A. To segregate storage into multiple pools with different performance characteristics
  B. To facilitate normal or high redundancy ASM diskgroups
  C. To enable disk mirroring for the system area
  D. To segregate storage into multiple pools that can be assigned to different databases
  E. To segregate storage into multiple pools that can be assigned to different resource consumer groups in the same database.
  B. To facilitate normal or high redundancy ASM diskgroups
  D. To segregate storage into multiple pools that can be assigned to different databases

  ---

  Creating multiple grid disks per cell disk allows you to create multiple pools of storage on the same Exadata Storage Server.The multiple grid disks can be assigned to separate ASM diskgroups, which can be provisioned to different

  databases.

  Note:

  *Celldisks are the third layer of abstraction. It was introduced to enable interleaving in the first place

  *Griddisks are the fourth layer of abstraction, and they will be the Candidate Disks to build your ASM diskgroups from.

  * The first grid disk created on the cell disk will allocate space from the outer tracks and move towards the inner tracks, reserving the number of tracks that correspond to the size of the grid disk.This grid disk provides the fastest performance since the outer tracks of a hard disk provide the best read/write performance.The next grid disk you will create starts from the tracks where the first grid disk ends, and this process repeats until you exhaust all the space on the cell disk or you are done creating the grid disks.

• Question 28:

  Which two are true about the use of DBFS in a Database Machine environment?

  A. DBFS must be used to bulk load data into a database on the Database Machine if the staging area requires Exadata based shared storage.
  B. DBFS must be used to have a POSIX compliant shared storage solution that is accessible from the database servers on a Database Machine.
  C. DBFS must be used to bulk load data into a production database on the Database Machine.
  D. DBFSmust use the DBFS_DG diskgroup for any DBFS store.
  E. DBFS must be used to have a POSIX-compliant Exadata-based shared storage solution.
  A. DBFS must be used to bulk load data into a database on the Database Machine if the staging area requires Exadata based shared storage.
  B. DBFS must be used to have a POSIX compliant shared storage solution that is accessible from the database servers on a Database Machine.

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  Note:

  *external tables on DBFS file-systems provide the probably the most high-performance way to bulk load data into your database.

• Question 29:

  You are using Hybrid Columnar Compression for a table stored in a tablespace that is contained in an Exadata-based ASM diskgroup. Identify three statements that correctly explain where the compression and decompression can be done.

  A. Decompression can be done on the database servers.
  B. Compression can be done on the Exadata storage servers.
  C. Compression can be done on the database servers.
  D. Decompression can be done on the Exadata storage servers.
  A. Decompression can be done on the database servers.
  B. Compression can be done on the Exadata storage servers.
  D. Decompression can be done on the Exadata storage servers.

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  B:

  *Exadata storage provides an advanced compression technology, Hybrid Columnar Compression, that typically provides 10x, and higher, levels of data compression.

  *The Exadata Storage Server (Exadata storage or Exadata cells) is used as the storage for the Oracle Database in the Database Machine. It runs the Exadata Storage Server Software that provides the unique and powerful Exadata technology including Smart Scan, Smart Flash Cache, Smart Flash Logging, IO Resource Manager, Storage Indexes and Hybrid Columnar Compression.

  A, D: *decompression /Queries run directly on Hybrid Columnar Compressed data does not require the data to be decompressed /Data that is required to satisfy a query predicate does not need to be decompressed; only the columns and rows being returned to the client are decompressed in memory /The decompression process typically takes place on the Oracle Exadata Storage Server in order to maximize performance and offload processing from the database server.

• Question 30:

  Which three are true regarding the use of Storage Indexes?

  A. Different storage regions may have different columns indexed for the same table.
  B. A Storage index is automatically maintained by CELLSRV based on the filter columns of the offload SQL.
  C. The use of Storage indexes for a particular database can be disabled by using an I/O Resource Manager Database Plan.
  D. Storage Indexes occupy space in the Smart Flash Cache.
  E. The use of Storage Indexes for particular categories of I/O can be disabled by using an I/O Resource Manager Category Plan.
  F. A maximum of eight table columns for any table are Indexed per storage region.
  B. A Storage index is automatically maintained by CELLSRV based on the filter columns of the offload SQL.
  C. The use of Storage indexes for a particular database can be disabled by using an I/O Resource Manager Database Plan.
  F. A maximum of eight table columns for any table are Indexed per storage region.

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  F, not D: Each disk in the Exadata storage cell is divided into equal sized pieces called storage regions (default 1MB). There is an index entry for every storage regions (1MB of data stored on disk). Each entry contains the minimum and maximum value for columns seen in `where' clause predicates. Information for up to 8 columns can be stored. The index is then used to eliminate disk IO by identifying which storage regions don't match the `where' clause of a query.

  Note: *Storage indexes are used during smart scans. All the limitations to smart scans apply to storage indexes. They do not work with joins. Bind variables are supported, however it's slightly more restrictive than regular indexes/queries. *The storage index is stored in the memory on each of the Exadata storage cells and is created and maintained transparently. However, if a storage cell is shutdown or rebooted the storage index will be lost from memory and will be recreated on subsequent accesses to the data after the cell has been brought back online. *Storage Indexes are a very powerful capability provided in Exadata storage that helps avoid I/O operations. The Exadata Storage Server Software creates and maintains a Storage Index (that is, metadata about the database objects) in the Exadata cell. The Storage Index keeps track of minimum and maximum values of columns for tables stored on that cell. When a query specifies a WHERE clause, but before any I/O is done, the Exadata software examines the Storage Index to determine if rows with the specified column value exist in the cell by comparing the column value to the minimum and maximum values maintained in the Storage Index. If the column valueis outside the minimum and maximum range, scan I/O for that query is avoided. Many SQL Operations run dramatically faster because large numbers of I/O operations are automatically replaced by a few lookups. To minimize operational overhead, Storage Indexes are created and maintained transparently and automatically by the Exadata Storage Server Software.