While Checking the status of database resources, ASM was shown as UNKNOWN on one node of a two node RAC.
$ crs_stat -t
Name Type Target State Host
------------------------------------------------------------
ora.orcl.db application ONLINE ONLINE rac1
ora....11.inst application ONLINE ONLINE rac1
ora....SM1.asm application ONLINE ONLINE rac1
ora....DC.lsnr application ONLINE ONLINE rac1
ora....idc.gsd application ONLINE ONLINE rac1
ora....idc.ons application ONLINE ONLINE rac1
ora....idc.vip application ONLINE ONLINE rac1
ora....SM2.asm application ONLINE UNKNOWN rac2
ora....C2.lsnr application ONLINE ONLINE rac2
ora....dc2.gsd application ONLINE ONLINE rac2
ora....dc2.ons application ONLINE ONLINE rac2
ora....dc2.vip application ONLINE ONLINE rac2
Following error was coming while trying to start the +ASM2 instance with SRVCTL:
$srvctl start asm -n rac2
PRKS-1009 : Failed to start ASM instance "+ASM2" on node "rac2",
[CRS-0223: Resource 'ora.rac2.ASM2.asm' has placement error.]
While trying to start the same with crs_start :
$ crs_start -f ora.rac2.ASM2.asm
CRS-1028: Dependency analysis failed because of:
'Resource in UNKNOWN state: ora.rac2.ASM2.asm'
CRS-0223: Resource 'ora.rac2.ASM2.asm' has placement error
There are two ways to come out of this UNKNOWN state of resources:
1. Start the resource from sqlplus
2. Use crs_stop -f to clear the state of database resources.
$ export ORACLE_HOME=+ASM2 $ sqlplus "/ as sysdba" SQL > startup Diskgroup mounted
It will go fine and the +ASM2 instnace will be started.
$ crs_stop -f ora.rac2.ASM2.asm
This will clear the UNKNOWN state and will make the resource as OFFLINE.
Now start the resource as:
$ srvctl start asm -n rac2
After using this check the status :
$ crs_stat -t
Name Type Target State Host
------------------------------------------------------------
ora.orcl.db application ONLINE ONLINE rac1
ora....11.inst application ONLINE ONLINE rac1
ora....SM1.asm application ONLINE ONLINE rac1
ora....DC.lsnr application ONLINE ONLINE rac1
ora....idc.gsd application ONLINE ONLINE rac1
ora....idc.ons application ONLINE ONLINE rac1
ora....idc.vip application ONLINE ONLINE rac1
ora....SM2.asm application ONLINE ONLINE rac2
ora....C2.lsnr application ONLINE ONLINE rac2
ora....dc2.gsd application ONLINE ONLINE rac2
ora....dc2.ons application ONLINE ONLINE rac2
ora....dc2.vip application ONLINE ONLINE rac2

Excellent. Very useful.
Thanks
Murali