052-229(新增70题2018)
Redo log files are multiplexed in your database. The disk in which you have one of the redo log members is highly fragmented. In the process of defragmentation you lose the redo log member, which is not a member of the current group.
How would you recover from the loss of the redo log member?
A. SMON would automatically restore the lost file.
B. You would need to restore the whole database from the last backup.
C. You would need to restore the file from the last full database backup.
D. You would need to use flashback technology to restore the lost redo log member.
E. You would need to use Recovery Manager (RMAN) to restore the lost redo log member.
F. You would need to restore the missing log file by copying one of the remaining files from the same group.
Answer: F
To protect against a failure involving the redo log itself, Oracle Database allows a multiplexed redo log, meaning that two or more identical copies of the redo log can be automatically maintained in separate locations. For the most benefit, these locations should be on separate disks. Even if all copies of the redo log are on the same disk, however, the redundancy can help protect against I/O errors, file corruption, and so on. When redo log files are multiplexed, LGWR concurrently writes the same redo log information to multiple identical redo log files, thereby eliminating a single point of redo log failure.
Multiplexing is implemented by creating groups of redo log files. A group consists of a redo log file and its multiplexed copies. Each identical copy is said to be a member of the group. Each redo log group is defined by a number, such as group 1, group 2, and so on.
