oracle 11g rac asm ORA-15064错误

数据库是11.2.0.3.0 的rac

在使用impdp导入数据时导入进程终止了.
后检查告警日志发现如下信息

Time drift detected. Please check VKTM trace file for more details.
Thu Mar 28 05:45:49 2013
Time drift detected. Please check VKTM trace file for more details.
Thu Mar 28 07:28:47 2013
Time drift detected. Please check VKTM trace file for more details.
Thu Mar 28 09:06:15 2013
Time drift detected. Please check VKTM trace file for more details.
Thu Mar 28 09:44:25 2013
NOTE: ASMB terminating
Errors in file /oracle/diag/rdbms/xtybdata/xtybdata1/trace/xtybdata1_asmb_3802094.trc:
ORA-15064: communication failure with ASM instance
ORA-03113: end-of-file on communication channel

是asm实例出了故障
检查asm的告警日志

*** 2013-03-28 09:44:25.446
NOTE: ASMB terminating
ORA-15064: communication failure with ASM instance
ORA-03113: end-of-file on communication channel
Process ID:
Session ID: 961 Serial number: 3
error 15064 detected in background process
ORA-15064: communication failure with ASM instance
ORA-03113: end-of-file on communication channel
Process ID:
Session ID: 961 Serial number: 3
kjzduptcctx: Notifying DIAG for crash event
----- Abridged Call Stack Trace -----
ksedsts()+360< -kjzdssdmp()+240<-kjzduptcctx()+228<-kjzdicrshnfy()+100<-ksuitm()+5124<-ksbrdp()+4508<-opirip()+1624<-opidrv()+608<-sou2o()+136<-opimai_real()+188<-ssthrdmain()+268<-main()+204<-__start()+112
----- End of Abridged Call Stack Trace -----

*** 2013-03-28 09:44:25.473
ASMB (ospid: 3802094): terminating the instance due to error 15064

*** 2013-03-28 09:44:29.630
ksuitm: waiting up to [5] seconds before killing DIAG(4063788)

这也没有指出特定的原因,重启该节点,数据库起来了,但是问题的根本原因还是没找到