[oracle@zrh ~]$ sqlplus sys/sys as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Sun Nov 25 12:04:15 2012
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
SQL> CONNECT / AS SYSDBA
Connected to an idle instance.
SQL> startup
ORACLE instance started.
Total System Global Area 1071333376 bytes
Fixed Size 1341312 bytes
Variable Size 620759168 bytes
Database Buffers 444596224 bytes
Redo Buffers 4636672 bytes
Database mounted.
ORA-01034: ORACLE not available
ORA-27102: out of memory
Linux Error: 12: Cannot allocate memory
Additional information: 1
Additional information: 163842
Additional information: 8
SQL> sqlplus scott/tiger
SP2-0734: unknown command beginning "sqlplus sc..." - rest of line ignored.
SQL> connect/as sysdba;
Connected to an idle instance.
SQL> shutdown immediate;
ORA-01034: ORACLE not available
ORA-27102: out of memory
Linux Error: 12: Cannot allocate memory
Additional information: 1
Additional information: 163842
Additional information: 8
内存 不足吧 memory_target设了多少？调低一些