ASM2.asm:SQL> ORA-29760: instance_number parameter not specified

Our ASM db wont start on a RAC cluster using srvctl started throwing the below error

ASM2.asm:SQL> ORA-29760: instance_number parameter not specified

where it starts fine with sqlplus on node-2 without any issue.

to further troubleshhot turn on the srvctl trace

export SRVM_TRACE=TRUE

now issue the same command

srvctl start asm -n

clearly evident that it is using spfile which was stored from the previous run and the spfile has
some wrong configuration. so made the below changes in the

1) add these is pfile with other memory parameters
instance_type='asm'
+ASM1.instance_number=1
+ASM2.instance_number=2
cluster_database_instances=2
cluster_database = TRUE

2) start the asm instance and recreate the spfile
3) shutdown and point the spfile in the pfile
4) try with srvctl now

Now all is gud

my both ASM instances came back fine using srvctl ..