关键字：
rman不能备份
作者：
jlandzpa

released channel: t1
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-12001: could not open channel t2
RMAN-10008: could not create channel context
RMAN-10003: unable to connect to target database using connect string "oraback/xxxxxx@xxxx"
ORA-01031: insufficient privileges
该用户已经授了sysdba角色.
解决方法：grant sysdba to username；需要在两个节点都执行。
因为，登录时需要检查节点上的口令文件，
而grant sysdba to username命令只会更改当前节点的口令文件。