Tonight,after I did some changes on the parameter(processes,changed it from 150 default to 2),I issued the commands below:

SQL> alter system set processes=2 scope=spfile;

System altered.

SQL> shutdown immediate;

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup;

ORA-03113: end-of-file on communication channel

SQL> !oerr ora 03113

03113, 00000, “end-of-file on communication channel”

// *Cause: The connection between Client and Server process was broken.

// *Action: There was a communication error that requires further investigation.

//          First, check for network problems and review the SQL*Net setup.

//          Also, look in the alert.log file for any errors. Finally, test to

//          see whether the server process is dead and whether a trace file

//          was generated at failure time.

So,I got the error  ORA-03113,now I know the reason for this is that i changed the ‘process’ parameter to a too small.But I didn’t know the truly fact.

After that,i had to connect again,and startup the database using a pfile,and recreate a new spfile from the pfile.