系统挂起

今天系统使用人员反映系统登录很慢。
查看了一下v$session，发现有很多session。
系统基本不能使用DML。

检查一下alert，发现下面的内容：
Wed Apr 25 09:05:43 2007
Database Characterset is AL32UTF8
replication_dependency_tracking turned off (no async multimaster replication found)
Completed: ALTER DATABASE OPEN
Wed Apr 25 23:16:37 2007
ORACLE Instance mycim - Can not allocate log, archival required
Wed Apr 25 23:16:37 2007
ARCH: Connecting to console port...
Thread 1 cannot allocate new log, sequence 44
All online logs needed archiving
Current log# 1 seq# 43 mem# 0: /u1/oracle/product/9.2/oradata/mycim/redo01.log

SQL> archive log list
Database log mode              Archive Mode
Automatic archival             Disabled
Archive destination            /u1/logs/archives
Oldest online log sequence     41
Next log sequence to archive   43
Current log sequence           43

SQL> alter system set log_archive_start=true scope=spfile;

System altered.

SQL> archive log start