111 To enable faster incremental backups, you enabled block change tracking for the database. Which

111

To enable faster incremental backups, you enabled block change tracking for the database.

Which two statements are true about the block change tracking file? (Choose two.)

A. Multiple change tracking files can be created for a database.

B. The change tracking file must be created after the first level 0 backup.

C. RMAN does not support backup and recovery of the change tracking file.

D. The database clears the change tracking file and starts tracking changes again, after whole database

restore and recovery operations.

Correct Answer: CD

Section: (none)

Explanation

Explanation/Reference:

block change tracking介绍

Block chage tracking是Oracle10g的一个新特性，Block change tracking进程记录自从上一次备份以来数据块的变化，并把这些信息记录在跟踪文件中。RMAN使用这个文件判断增量备份中需要备份的变更数据。这极大的促进了备份性能，RMAN可以不再扫描整个文件以查找变更数据。
为此Oracle引入了一个新的后台进程，CTWR，其全称为Change Tracking Writer，用于记录变化的块并将变化写入相应的日志文件中。

Location of the Block Change Tracking File

One block change tracking file is created for the whole database. By default, the change tracking file is created as an Oracle
managed file in the destination specified by the

DB_CREATE_FILE_DEST

initialization
parameter. You can also place the change tracking file in any location that you choose, by specifying its name when enabling block change tracking. Oracle recommends against using a raw device (that is, a disk without a file system) as a change tracking file.

Note:
In an Oracle RAC environment, the change tracking file must be located on shared storage accessible from all nodes in the cluster.

RMAN does not support backup and recovery of the change tracking file. The database resets the change tracking file when it determines that the change tracking file is invalid. If
you restore and recover the whole database or a subset, then the database resets the block change tracking file and starts tracking changes again. After
you make a level 0 incremental backup, the next incremental backup can use change tracking data.