[bbk4345]小布-OCP 042全真试题讲解

youngfan007

　　参考视频:
　　[bbk4345]小布-OCP 042全真试题讲解
　　在非归档模式下，你只能做冷备；做热备是无法保证数据的一致性的.
　　在归档模式下，是可以做热备的，其原理是根据归档日志文件来实现数据的一致性.

• 1、Your test database is running in NOARCHIVELOG mode.What are the implications of this?
  
  
  
  • You can perform open database backups.
    
  • You can perform closed database backups.
    
  • You cannot perform schemal-level logical backups.
    
  • You can perform the backup of only the SYSTEM tablespace when the databse is open.
    
  
  
• 2、Which two statements about Recovery Manager(RMAN) backups are true?(Choose two)
  
  
  
  • A.Online redo log files can be backed up.
    
  • B.Archived redo log files are backed up.
    
  • C.Only used data blocks can be backed up as backup sets.
    
  • D.Only consistent database backups can be performed.
    
  • E.RMAN backup can be taken if the database is configureed in ARCHIVELOG mode.
    
  
  

　　在非归档模式下，RMAN是可以备份数据库的，不过必须把数据库设置成为mount状态.
　　使用RMAN备份数据库，只备份Data Files 和 Archive log  file.

• 3、The database is open,and you plan to perform Recovery Manager(RMAN)backups.Which three statements are true about these backups?(Choose trhee)
  
  
  
  • A.The backups would be consistent.
    
  • B.The backups would be inconsistent.
    
  • C.The backups need to be restored and database has to be recovered in case of a media failure.
    
  • D.The backups need not be restored during recovery in case of a media failure.
    
  • E.The backups would be possible only if the database is running in ARCHIVELOG mode.
    
  • F.The backups would be possible only if the database is running in NOARCHIVELOG mode.
    
  
  

　　restore就是拷贝备份集，recovery就是利用归档日志文件更新备份集，是备份集达到你任何想要的状态.
　　恢复的时候，肯定是先restore，然后再recovery.
　　在数据库打开的状态下，使用RMAN进行备份，数据库必须处于归档模式下.

• 4、You perform differential incremental level 1 backups of your database on each working day and level 0 backup on Sundays.
  
  
  
  • Which two statements are true about the differential incremental backups?(choose two)
    
  • A.The backup performed on Sundays contains all the blocks that have ever been use in the database.
    
  • B.The backup performed on Sundays contains all the blocks that have changed since the last level 1 backup.
    
  • C.The backup performed on each working day contains all the blocks that have changed since the last level 0 or level 1 backup.
    
  • D.The backup performed on each working day contains all the blokcs that have changed since the last level 0 backup.
    
  
  

　　level 0相当于一种特殊的增量备份.
　　level 0就相当于全备,但是0级备份不等于全备.其中全备不能作为增量备份的基础，而0级备份则可以作为增量备份的基础.
　　0级备份的定义（全备），就是:The backup performed on Sundays contains all the blocks that have ever been use in the database.

• 5、According to your backup strategy,you performed an incremental level 0 backup of your database.Which statement regarding this backup is true?
  
  
  
  • A.The backup is similar to image copy.
    
  • B.The backup contains all used data blocks.
    
  • C.The backup contains only unused data blocks.
    
  • D.The backup contains all data blocks changed since the last incremental level 1 backup.
    
  
  

　　image copy类似于cp,dd命令的备份，而level 0的备份属于备份集的备份，有着本质的区别.

• 6、On which three can you use Recovery Manager(RMAN) to perform incremental backup ?(Choose three)
  
  
  
  • A.data files
    
  • B.control files
    
  • C.tablespaces
    
  • D.password files
    
  • E.parameter file
    
  • F.whole database
    
  • G.flashback log file
    
  • H.archived log file
    
  • I.change tracking file
    
  
  

　　增量备份主要是针对于数据文件块的备份，只把那些变化的块备份下来.  
　　控制文件是不分块的，RMAN备份只是镜像的拷贝.
　　flashback log file、archive log file、change tracking file是对整个数据库文件的拷贝，不分块的概念的.因此不能进行增量备份.

• 7、You backed up the control file to trace.Which statement is true about the trace file generated?
  
  
  
  • A.The trace file is in binary format.
    
  • B.The trace file has a SQL script to re-create the control file.
    
  • C.The trace file is a backup set created during the backup of the control file.
    
  • D.The trace file contains the instructions to manually re-create the control file.
    
  • E.The trace file is an image copy of the control file created during the backup of the control file.
    
  
  

　　trace file一般就是日志文件，日志文件一般就是文本文件.
　　trace file没有备份集的概念的，备份集的概念是针对于数据文件的.
　　所谓的image copy就是二进制文件.

• 8、Your database is in NOARCHIVELOG mode,after which two operations you should take the backup of control file?(Choose two)
  
  
  
  • A.adding a new user to the database
    
  • B.dropping a user from the database
    
  • C.dropping a table from the database
    
  • D.dropping a data file from a tablespace
    
  • E.adding a new tablespace to the database.
    
  
  

　　什么时候需要备份控制文件，肯定是当控制文件的内容发生变化了，才会进行备份.
　　控制文件主要记录了数据库的结构化的信息.

• 9、You executed the following command to back up your control file:
  

　　ALTER DATABASE BACKUP CONTROLFILE TO TRACE;
　　Which initialization parameter is used to specify the location of the trace file?

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  • A.USER_DUMP_DEST
    
  • B.CORE_DUMP_DEST
    
  • C.TRACE_DUMP_DEST
    
  • D.BACKUP_DUMP_DEST
    
  • E.BACKGROUND_DUMP_DEST
    
  
  

　　Your database is configured in NOARCHIVELOG mdoe.All the control files have been lost due to a hard disk failure bu the data files are not lost.You have the closed whole database backup available to you.
　　那么这种情况下，你能否重构数据文件呢?答案不能.因为数据库时处于非归档模式下.

• 10、Your database is configured in NOARCHIVELOG mode.All the control files have been lost due to a hard disk failure but the data files are not lost.You have closed whole database backup availbale to you.
  

　　Which two statements are true in this scenario?(Choose two)

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  • A.the instance aborts.
    
  • B.The database cannot be recovered.
    
  • C.The database can be recovered by restoring the control files from the backup.(时间点不一致，无法通过拷贝方式，直接使用控制文件)
    
  • D.The database remains opened and you have to shut it down with the ABORT option.
    
  • E.The database can be restored till the point of the last closed whole database backup.
    
  
  
• 11、In your database,the Log Writer(LGWR)process is unable to write to a member of a current redo log group due to read/write failure.Which two effects would you see in your database?(Choose two)
  
  
  
  • A.the database instance aborts.
    
  • B.the database operation temporaily halts till the member becomes available.
    
  • C.Writing proceeds as normal.LGWR writes to the available members of a group and ignores the unavailable members.
    
  • D.The member would be marked as STALE and an error message would be written to the alert log file and LGWR trace file.
    
  • E.The status of the group changes to INACTIVE and an error message would be written to the alert log file and LGWR trace file.
    
  
  

　　log file group的状态，CURRENT、INACTIVE、STALE
　　当前正在使用的日志组的状态为:CURRENT
　　即将或者正在进行归档的日志文件为:INACTIVE
　　脏了的日志文件为STALE.