数据库使用一个月了，突然挂掉：错误代码17002 io异常:read timeout
解决：
1.登陆sql命令窗口
[oracle@hostname ~]$ sqlplus /nolog
SQL*Plus: Release 11.2.0.1.0 Production on Fri Aug 28 10:58:59 2015
Copyright (c) 1982, 2009, Oracle. All rights reserved.
2.以管理员身份连接到数据库
SQL> connect sys/oracle as sysdba
Connected.
3.关闭数据库实例
SQL> shutdown abort
ORACLE instance shut down.
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, Oracle Label Security, OLAP, Data Mining,
Oracle Database Vault and Real Application Testing options
4.查看监听并关闭
[oracle@hostname~]$ lsnrctl status
[oracle@hostname~]$ lsnrctl stop
LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 28-AUG-2015 11:15:32
Copyright (c) 1991, 2009, Oracle. All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=iZ11gqfg6h1Z)(PORT=1521)))
The command completed successfully
5.重启监听
[oracle@hostname~]$ lsnrctl start
6.重启数据库
[oracle@hostname~]$ sqlplus /nolog
SQL*Plus: Release 11.2.0.1.0 Production on Fri Aug 28 11:30:25 2015
Copyright (c) 1982, 2009, Oracle. All rights reserved.
SQL> connect / as sysdba
Connected to an idle instance.
SQL> startup
ORACLE instance started.
Total System Global Area 1486495744 bytes
Fixed Size 2213496 bytes
Variable Size 1124075912 bytes
Database Buffers 352321536 bytes
Redo Buffers 7884800 bytes
Database mounted.
Database opened.
特别需要注意的是，一定要先启动监听服务，再启动数据库，否则还是连不上的。
查看oracle 数据库服务：lsnrctl status