I have two node RAC(220.127.116.11) on Windows 2008R2. I used asmca to create diskgroups and it was detecting the disks. After creating i see in ASM instance, asm_diskstring parameter value as blank. Is it expected behavior in Windows 2008R2. But everything is working fine.
Please let me know if we need to modify this.
Yes, it is expected behaviour. The ASM instance will still search in platform-specific default locations and find the disks there.
Similarly, if you use ASMLib on Linux, there is no need to sem asm_diskstring.