今天重新建了一个库，在执行
alter system switch logfile;时一直夯在那里，于是查看警报日志文件，有如下信息：
Thu Aug 21 19:25:30 2014
Errors in file /u01/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_arc0_15710.trc:
ORA-19504: failed to create file "/u01/app/archivelog/dest2/1_4_856205535.dbf"
ORA-27040: file create error, unable to create file
Linux Error: 13: Permission denied
ARC0: Error 19504 Creating archive log file to '/u01/app/archivelog/dest2/1_4_856205535.dbf'
Errors in file /u01/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_arc0_15710.trc:
ORA-19504: failed to create file "/u01/app/archivelog/dest1/1_4_856205535.dbf"
ORA-27040: file create error, unable to create file
Linux Error: 13: Permission denied
ARC0: Error 19504 Creating archive log file to '/u01/app/archivelog/dest1/1_4_856205535.dbf'
ARCH: Archival stopped, error occurred. Will continue retrying
ORACLE Instance orcl - Archival Error
ORA-16038: log 1 sequence# 4 cannot be archived
ORA-19504: failed to create file ""
ORA-00312: online log 1 thread 1: '/u01/app/oracle/oradata/orcl/redo01.log'
Errors in file /u01/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_arc0_15710.trc:
ORA-16038: log 1 sequence# 4 cannot be archived
ORA-19504: failed to create file ""
ORA-00312: online log 1 thread 1: '/u01/app/oracle/oradata/orcl/redo01.log'
Thu Aug 21 19:25:32 2014
ARCH: Archival stopped, error occurred. Will continue retrying
ORACLE Instance orcl - Archival Error
ORA-16014: log 1 sequence# 4 not archived, no available destinations
ORA-00312: online log 1 thread 1: '/u01/app/oracle/oradata/orcl/redo01.log'
Errors in file /u01/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_arc1_15712.trc:
ORA-16014: log 1 sequence# 4 not archived, no available destinations
ORA-00312: online log 1 thread 1: '/u01/app/oracle/oradata/orcl/redo01.log'

由此我们可知可能文件已满，或者归档目录不存在了。
经查明，文件并未满，而且目录也存在。
后来发现时目录权限的问题。我的dest1,dest2的权限是root，应该为oracle才对。
于是修改权限，问题解决。