关于rman备份的问题

   昨天调整了数据库的参数，见下：
ALTER SYSTEM SET memory_target='7200000000' SCOPE=BOTH;
ALTER SYSTEM SET pga_aggregate_target='600000000' SCOPE=BOTH;
ALTER SYSTEM SET db_cache_size='3600008000' SCOPE=BOTH;
ALTER SYSTEM SET shared_pool_size='600M' SCOPE=BOTH;
   今天早上查看数据库备份情况，发现没有生成备份，手动执行报以下错误：
[oracle@eytdb ~]$ rman target /;
恢复管理器: Release 11.2.0.2.0 - Production on 星期四 10月 20 11:54:15 2011
Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

DBGSQL:  TARGET> select count(*) into :dbstate from v$parameter where lower(name) = '_dummy_instance' and upper(value) = 'TRUE'
DBGSQL:   sqlcode = 1008
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-00554: 内部恢复管理器程序包初始化失败
RMAN-06003: 来自目标数据库的 ORACLE 错误:
ORA-01008: 并非所有变量都已绑定  

告警日志 alert_eytdbs.log 错误见下：
  
Exception [type: SIGSEGV, SI_KERNEL(general_protection)] [ADDR:0x0] [PC:0x1E79F8F, kkslMarkLiteralBinds()+225] [flags: 0x0, count: 1]
Errors in file /home/oracle/app/diag/rdbms/eytdbs/eytdbs/trace/eytdbs_ora_28360.trc  (incident=32353):
ORA-07445: �虹�板�甯搁��璇�: �稿�杞��� [kkslMarkLiteralBinds()+225] [SIGSEGV] [ADDR:0x0] [PC:0x1E79F8F] [SI_KERNEL(general_protection)] []
Incident details in: /home/oracle/app/diag/rdbms/eytdbs/eytdbs/incident/incdir_32353/eytdbs_ora_28360_i32353.trc
Use ADRCI or Support Workbench to package the incident.
See Note 411.1 at My Oracle Support for error and packaging details.
Thu Oct 20 02:00:06 2011
Dumping diagnostic data in directory=[cdmp_20111020020006], requested by (instance=1, osid=28360), summary=[incident=32353].
Thu Oct 20 02:00:07 2011
 
/home/oracle/app/diag/rdbms/eytdbs/eytdbs/trace/eytdbs_ora_28360.trc 见下：

Exception [type: SIGSEGV, SI_KERNEL(general_protection)] [ADDR:0x0] [PC:0x1E79F8F, kkslMarkLiteralBinds()+225] [flags: 0x0, count: 1]
Incident 32353 created, dump file: /home/oracle/app/diag/rdbms/eytdbs/eytdbs/incident/incdir_32353/eytdbs_ora_28360_i32353.trc
ORA-07445: 出现异常错误: 核心转储 [kkslMarkLiteralBinds()+225] [SIGSEGV] [ADDR:0x0] [PC:0x1E79F8F] [SI_KERNEL(general_protection)] []
ssexhd: crashing the process...
Shadow_Core_Dump = partial

    查ora-07445 网上说是oracle的BUG，是否是BUG就不清楚了（数据库是1.2.0.2.0 ，操作系统是Red Hat Enterprise Linux  6.0 (Santiago)，内存MemTotal:  20458656 kB），但一定与昨天的参数修改有关，把修改的参数值再改回去，还是不能rman，，后来查 ORA-01008: 并非所有变量都已绑定，是参数cursor_sharing 引起的，当时值为SIMILAR，改为force，还是不能rman，最后改为exact 。ALTER SYSTEM SET cursor_sharing='exact'; rman可以正常使用了。但是到底是什么原因引起的呢？