现象：
RAC的一个节点起不来，crs_stat查看发现很多资源状态都为offline
[Oracle@rac1 ~]$ crs_stat -t
Name Type Target State Host
------------------------------------------------------------
ora.rac.db application OFFLINE OFFLINE
ora....c1.inst application ONLINE OFFLINE
ora....c2.inst application ONLINE OFFLINE
ora....test.cs application OFFLINE OFFLINE
ora....ac1.srv application OFFLINE OFFLINE
ora....ac2.srv application OFFLINE OFFLINE
ora....SM1.asm application ONLINE ONLINE rac1
ora....C1.lsnr application ONLINE ONLINE rac1
ora....ac1.gsd application ONLINE ONLINE rac1
ora....ac1.ons application ONLINE ONLINE rac1
ora....ac1.vip application ONLINE ONLINE rac1
ora....SM2.asm application ONLINE UNKNOWN rac2
ora....C2.lsnr application ONLINE UNKNOWN rac2
ora....ac2.gsd application ONLINE ONLINE rac2
ora....ac2.ons application ONLINE ONLINE rac2
ora....ac2.vip application ONLINE ONLINE rac2
[oracle@rac1 ~]$ srvctl start asm -n rac2
PRKS-1009 : Failed to start ASM instance "+ASM2" on node "rac2", [PRKS-1009 : Failed to start ASM instance "+ASM2" on node "rac2", [CRS-1028: Dependency analysis failed because of:
CRS-0223: Resource 'ora.rac2.ASM2.asm' has placement error.]]
[PRKS-1009 : Failed to start ASM instance "+ASM2" on node "rac2", [CRS-1028: Dependency analysis failed because of:
CRS-0223: Resource 'ora.rac2.ASM2.asm' has placement error.]]
[oracle@rac1 ~]$ srvctl stop asm -n rac2
[oracle@rac1 ~]$ srvctl start asm -n rac2
PRKS-1009 : Failed to start ASM instance "+ASM2" on node "rac2", [PRKS-1009 : Failed to start ASM instance "+ASM2" on node "rac2", [CRS-0215: Could not start resource 'ora.rac2.ASM2.asm'.]]
[PRKS-1009 : Failed to start ASM
stop之后再start还是不行。

分析：
资源状态因为某种原因变为UNKNOWN，导致无法通过正常方式启动。

解决方法：
客户的系统比较重要，当时先恢复业务，再仔细分析原因。
恢复业务的方法如下：
先强制停止状态为UNKNOWN的资源：
crs_stop -f ora.rac2.ASM2.asm
crs_stop -f ora.rac2.lsnr
再重新启动资源： 
crs_start -all
重启之后业务恢复正常。