Oracle 11gR2 ASM Spfile is in Disk Group ( How ASM starts then?)

I recently got very intresting confusion ASM Spfile is stored in ASM diskgroup in 11gR2 in first default diskgroup created during GI installtion and in order to start ASM we need spfile.
So if my ASM is down, how do i start it as my Spfile lies in ASM diskgroup.

Here lies the answer to this question:

$ asmcmd spget
+DEV_DATA01/asm/asmparameterfile/registry.253.754437197

 

While Clusterware (GI) Startup GPnP ( Grid plug and play ) profile provides the ASM discovery string

$gpnptool getpval -asm_dis

ORCL:*

These string is used to scan the device headers which contain the ASM spfile i.e. (kfdhdb.spfflg=1).

$ asmcmd lsdsk -G RDPDEV_DATA01
Path
ORCL:ASMSDB12
ORCL:ASMSDB2
ORCL:ASMSDB3
ORCL:ASMSDB5

 
Let's scan above disk devices :

$ kfed read ORCL:ASMSDB12 | grep -E 'spf|ausize'
kfdhdb.ausize:                  1048576 ; 0x0bc: 0x00100000
kfdhdb.spfile:                        0 ; 0x0f4: 0x00000000
kfdhdb.spfflg:                        0 ; 0x0f8: 0x00000000

$ kfed read ASMSDB2  | grep -E 'spf|ausize'

$  kfed read ORCL:ASMSDB3  | grep -E 'spf|ausize'
kfdhdb.ausize:                  1048576 ; 0x0bc: 0x00100000
kfdhdb.spfile:                        0 ; 0x0f4: 0x00000000
kfdhdb.spfflg:                        0 ; 0x0f8: 0x00000000

$  kfed read ORCL:ASMSDB5  | grep -E 'spf|ausize'
kfdhdb.ausize:                  1048576 ; 0x0bc: 0x00100000
kfdhdb.spfile:                       19 ; 0x0f4: 0x00000013
kfdhdb.spfflg:                        1 ; 0x0f8: 0x0000000   --> here is your spfile on this disk

Final Story:

To read the ASM spfile during the ASM instance startup, it is not necessary to open the disk group. All information necessary to access the data is stored in the device's header. By the way, the same technique is used to access the Clusterware voting files which are also stored in an ASM disk group. In this case, Clusterware does not need a running ASM instance to access the cluster voting files:
grid@iudb007:~/ [+ASM5] kfed read ORCL:ASMSDB5 | grep vf
kfdhdb.vfstart:                     256 ; 0x0ec: 0x00000100 <- START offset of the voting file
kfdhdb.vfend:                       288 ; 0x0f0: 0x00000120 <- END offset of the voting file