环境：Oracle11.2.4.0RAC
问题描述：
CRS服务不正常，asmdiskgroup挂载不了,截图如下：

日志如下：
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WedJun2710:28:102018
sql>alterdiskgroupcrsmount
NOTE:cacheregisteredgroupCRSnumber=1incarn=0xdbd84eae
NOTE:cachebeganmount(notfirst)ofgroupCRSnumber=1incarn=0xdbd84eae
WARNING:detectedduplicatepathstothesamedisk:
'/dev/mapper/CRSp1'and
'/dev/dm-23'
Moretraceinformationdumpedto'/u01/app/grid/diag/asm/+asm/+ASM2/trace/+ASM2_ora_42445.trc'
WedJun2710:28:112018
ERROR:noreadquorumingroup:required2,found0disks
NOTE:cachedismounting(clean)group1/0xDBD84EAE(CRS)
NOTE:messagingCKPTtoquiescepinsUnixprocesspid:42445,image:oracle@db-5(TNSV1-V3)
NOTE:dbwrnotbeingmsg'dtodismount
NOTE:lgwrnotbeingmsg'dtodismount
NOTE:cachedismountedgroup1/0xDBD84EAE(CRS)
NOTE:cacheendingmount(fail)ofgroupCRSnumber=1incarn=0xdbd84eae
NOTE:cachedeletingcontextforgroupCRS1/0xdbd84eae
GMONdismountinggroup1at10forpid24,osid42445
ERROR:diskgroupCRSwasnotmounted
WARNING:DiskGroupCRScontainingspfileforthisinstanceisnotmounted
WARNING:DiskGroupCRScontainingconfiguredOCRisnotmounted
WARNING:DiskGroupCRScontainingvotingfilesisnotmounted
ORA-15032:notallalterationsperformed
ORA-15017:diskgroup"CRS"cannotbemounted
ORA-15063:ASMdiscoveredaninsufficientnumberofdisksfordiskgroup"CRS"
ERROR:alterdiskgroupcrsmount
WedJun2710:28:132018
NOTE:Noasmlibrariesfoundinthesystem
ERROR:-5(DuplicatediskDATA:DATA_0008)
ERROR:-5(DuplicatediskDATA:DATA_0001)
ERROR:-5(DuplicatediskDATA:DATA_0000)
ERROR:-5(DuplicatediskDATA:DATA_0003)
ERROR:-5(DuplicatediskCRS:CRS_0000)
ERROR:-5(DuplicatediskDATA:DATA_0007)
ERROR:-5(DuplicatediskDATA:DATA_0005)
ERROR:-5(DuplicatediskDATA2:DATA2_0002)
ERROR:-5(DuplicatediskDATA2:DATA2_0003)
ERROR:-5(DuplicatediskDATA:DATA_0004)
ERROR:-5(DuplicatediskRECOVERY:RECOVERY_0000)
ERROR:-5(DuplicatediskDATA:DATA_0002)
ERROR:-5(DuplicatediskDATA:DATA_0006)
ASMHealthCheckerfound1newfailures
------------------------------------------------------------------------------------

另一个节点正常，截图如下：

分析：

两边asm_diskstring的参数不同，

不正常的节点中asm_diskstring里存在指向重复的路径：
/dev/*，/dev/mapper/*
从而造成日志中的提示：
----------------------------
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尝试在不正常的节点下修改asm_diskstring，无法修改：

在正常的节点上执行：

altersystemsetasm_diskstring='/dev/dm-*'scope=spfile;

修改成功！

然后重启不正常的节点，重启后发现asm磁盘组挂载上了！