doubt in dynamic disk group

I created 3 volumes on the dynamic disk volume1, volume2, volume3, volume1 I am using in my App, I dismounted the volume1 and other two volumes volume2 and volume3 are online.
I restarted the machine, all three volumes volume1, volume2, volume3 are dismounting once the node is up.

I have tried creating volume on different disk , if any one volume is dismounted and re-start the machine, all the volume in dynamic disk are dismounted once node is up.

I am wondering if i dismount one volume all other volumes are dismounted once system is up, is there something we need to do with diskgroup. any help is appreciated.

Regards
Sharan