oracle数据库安装在阿里云上,一天收到以下告警: Name=ATABASENAME Type=Database Instance Host=iZW2519p6r9uZEEE Metric=Status Timestamp=Nov 17, 2014 4:16:37 AM CST Severity=Critical Message=Failed to connect to database instance: ORA-12519: TNS:no appropriate service handler found (DBD ERROR: OCIServerAttach). Rule Name=Database Availability and Critical States Rule Owner=SYSMAN 经查,此问题原因为进程数超出限制了,通过以下方法查询: # su - oracle $ sqlplus / as sysdba; 查看当前连接数: SQL> select count(*) from v$process; 查看到当前连接数为299 查看数据库允许的最大连接数: SQL> select value from v$parameter where name = 'processes'; 查看到允许的最大连接数为300 看来是连接数不够了,进行以下修改: 修改最大连接数为500: SQL> alter system set processes = 500 scope = spfile; 重启数据库: SQL> shutdown immediate; SQL> startup;