srvctl start database 报错，不要怕，先用sqlplus启动一下试试

用 srvctl 启动 RAC 数据库有时会起不来，例如：
oracle@testdb01 ~]$ srvctl start database -d orcl

PRCR-1079 : Failed to start resource ora.orcl.db

CRS-5017: The resource action "ora.orcl.db start" encountered the following error: 

ORA-27104: system-defined limits for shared memory was misconfigured

. For details refer to "(:CLSN00107:)" in "/u01/app/grid/diag/crs/testdb02/crs/trace/crsd_oraagent_oracle.trc". 


CRS-2674: Start of 'ora.orcl.db' on 'testdb02' failed


CRS-2632: There are no more servers to try to place resource 'ora.orcl.db' on that would satisfy its placement policy

CRS-5017: The resource action "ora.orcl.db start" encountered the following error: 

ORA-27104: system-defined limits for shared memory was misconfigured

. For details refer to "(:CLSN00107:)" in "/u01/app/grid/diag/crs/testdb01/crs/trace/crsd_oraagent_oracle.trc".


CRS-2674: Start of 'ora.orcl.db' on 'testdb01' failed

看着报错挺吓人，日志很高深。不要怕，先手工试试
[oracle@testdb01 ~]$ sqlplus / as sysdba
看看提示些啥，结合alert.log就比较好定位原因了。
这个例子就是内存参数设置太大了。
sqlplus / as sysdba
create pfile='/tmp/init.ora' from spfile='XXX';
修改正确的sga db_cache_size shared_pool_size参数后再
create spfile='+datadg/orcl/parameterfile/spfile_orcl_new' from pfile='/tmp/init.ora';
startup force 解决。