--执行日志切换时，夯住SQL> alter database add logfile group 4 (‘/u01/oradata/oracle/redo04.log‘) size 50m;SQL> alter system switch logfile;

[root@oracle archivelog]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/sda1              19G   14G  4.5G  75% /none                  506M  252M  254M  50% /dev/shmYou have new mail in /var/spool/mail/root[root@oracle archivelog]

alter database add logfile group 4 (‘/u01/oradata/oracle/redo04.log‘) size 50mCompleted: alter database add logfile group 4 (‘/u01/oradata/oracle/redo04.log‘) size 50mSat Nov 01 03:30:49 2014Thread 1 advanced to log sequence 163 (LGWR switch)  Current log# 4 seq# 163 mem# 0: /u01/oradata/oracle/redo04.logSat Nov 01 03:30:49 2014Errors in file /u01/diag/rdbms/oracle/beijing/trace/beijing_arc0_31059.trc:ORA-19815: WARNING: db_recovery_file_dest_size of 2147483648 bytes is 100.00% used, and has 0 remaining bytes available.************************************************************************You have following choices to free up space from recovery area:1. Consider changing RMAN RETENTION POLICY. If you are using Data Guard,   then consider changing RMAN ARCHIVELOG DELETION POLICY.2. Back up files to tertiary device such as tape using RMAN   BACKUP RECOVERY AREA command.3. Add disk space and increase db_recovery_file_dest_size parameter to   reflect the new space.4. Delete unnecessary files using RMAN DELETE command. If an operating   system command was used to delete files, then use RMAN CROSSCHECK and   DELETE EXPIRED commands.************************************************************************Errors in file /u01/diag/rdbms/oracle/beijing/trace/beijing_arc0_31059.trc:ORA-19809: limit exceeded for recovery filesORA-19804: cannot reclaim 24801792 bytes disk space from 2147483648 limit

SQL> startup nomount;SQL> show parameter db_recovery_file_dest_sizeSQL> Alter system set db_recovery_file_dest_size=2G scope=both;SQL> alter database mount;SQL> alter database open;

[root@oracle archivelog]# pwd/u01/flash_recovery_area/ORACLE/archivelog[root@oracle archivelog]# ls -ldrwxr-x---  2 oracle oinstall 4096 Nov  1 03:43 2014_10_29drwxr-x---  2 oracle oinstall 4096 Nov  1 03:43 2014_10_30drwxr-x---  2 oracle oinstall 4096 Nov  1 03:43 2014_10_31drwxr-x---  2 oracle oinstall 4096 Nov  1 03:44 2014_11_01[root@oracle archivelog]# rm -rf 2014_10_29[root@oracle archivelog]# rm -rf 2014_10_30[root@oracle archivelog]# rm -rf 2014_10_31

RMAN> crosscheck archivelog all;released channel: ORA_DISK_1allocated channel: ORA_DISK_1channel ORA_DISK_1: SID=42 device type=DISKvalidation failed for archived logarchived log file name=/u01/flash_recovery_area/ORACLE/archivelog/2014_10_31/o1_mf_1_159_b58hpwom_.arc RECID=155 STAMP=862437663validation succeeded for archived logarchived log file name=/u01/flash_recovery_area/ORACLE/archivelog/2014_11_01/o1_mf_1_160_b593tqck_.arc RECID=158 STAMP=862458264validation succeeded for archived logarchived log file name=/u01/flash_recovery_area/ORACLE/archivelog/2014_11_01/o1_mf_1_161_b593cqd6_.arc RECID=156 STAMP=862457783validation succeeded for archived logarchived log file name=/u01/flash_recovery_area/ORACLE/archivelog/2014_11_01/o1_mf_1_162_b593crx1_.arc RECID=157 STAMP=862457784Crosschecked 4 objectsRMAN>

crosscheck作用：更新存储仓库中的刚刚校验的对象的状态，便于后续操作处理校验对象：核对数据库、表空间、数据文件、控制文件、归档日志、SPFILE的备份集对象状态1.expired: 对象不存在于磁盘或磁带。当一个备份集处于expired状态，则该备份集中所有的备份片同样处于expired状态2.available: 对象处于可用状态。当一个备份集可用，则该备份集内的所有备份片同样可用3.unavailabe: 对象处于不可用状态。当一个备份集不可用，则该备份集内的所有备份片同样不可用

RMAN> DELETE EXPIRED  archivelog all;released channel: ORA_DISK_1allocated channel: ORA_DISK_1channel ORA_DISK_1: SID=42 device type=DISKList of Archived Log Copies for database with db_unique_name ORACLE=====================================================================Key     Thrd Seq     S Low Time ------- ---- ------- - ---------155     1    159     X 31-OCT-14        Name: /u01/flash_recovery_area/ORACLE/archivelog/2014_10_31/o1_mf_1_159_b58hpwom_.arcDo you really want to delete the above objects (enter YES or NO)? yesdeleted archived logarchived log file name=/u01/flash_recovery_area/ORACLE/archivelog/2014_10_31/o1_mf_1_159_b58hpwom_.arc RECID=155 STAMP=862437663Deleted 1 EXPIRED objectsRMAN>