635.While Monitoring the space usage in your database that is in ARCHIVELOG mode you observed that
the flash recovery area does not have enough free space to accommodate any more files and you do not
have necessary permissions to add more space to it.
Identify the two events that can occur in the event of a log switch? (Choose two.)
A. An entry is created in the alert log file and the database instance continues to function normally
B. The log switch hangs occur for transactions until free space is available in the flash recovery area
C. The Oracle database server deletes a file that is on the obsolete file list to make free space in the flash recovery area
D. The database instance status is implicitly changed to RESTRICTED mode and file creations to the flash recovery area are prevented
Answer: BC
答案解析：
参考：http://docs.oracle.com/cd/E11882_01/server.112/e10897/backrest.htm#ADMQS09211
题问：FRA空间满的情况下，并且你没有权限去扩充空间。此时数据库为归档模式，一般情况，归档日志是放在FRA中，如果FRA空间满，则在日志切换发生归档时，该事务会hang住，另外，在FRA空间满的情况下，数据库服务器会根据备份保留策略来删除过期的备份，已释放更多的空间。
About the Backup Retention Policy and the Fast Recovery Area
Space management in the fast recovery area is governed by a backup retention policy. A retention policy determines when files are obsolete, meaning that they are no longer needed to meet your data recovery objectives.
Retention policies can be based on redundancy of backups or on a recovery window (period of time). When using a policy based on redundancy, the fast recovery area considers a backup of a file obsolete only when the RMAN repository has records of a specified number of more recent backups of that file. When using a recovery policy based on a period of time (or window), you specify a time interval in days. Files are obsolete only when they are no longer needed for complete recovery or point-in-time recovery to a system change number (SCN) within the window. Therefore, a recovery retention policy based on a window is recommended.
Even after files in the fast recovery area are obsolete, they are typically not deleted until space is needed for new files. If space permits, files recently moved to tape remain on disk to avoid restoring them from tape for a recovery. The automatic deletion of obsolete files and files moved to tape from the fast recovery area makes it a convenient archiving destination. Other destinations require manual deletion of logs.