在NW7.6.5使用RMAN备份oralce DB时报错ORA-19506/ORA-27028/ORA-19511

NW7.6.5使用RMAN备份oralce DB时报错ORA-19506/ORA-27028/ORA-19511 released channel: t1 RMAN-00571: =========================================================== RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS =============== RMAN-00571: =========================================================== RMAN-03002: failure of backup plus archivelog command at 07/09/2014 14:00:32 ORA-19506: failed to create sequential file, name="onpcvct0_1_1", parms="" ORA-27028: skgfqcre: sbtbackup returned error ORA-19511: Error received from media manager layer, error text:  lnm_index_cfx_connect retry failed.  See privious error messages. (3:3:11) 1.已使用NSRCK -c / nsrck -L6进行检查,未见异常 请问如何修复index文件异常