Adding disk to existing diskgroup

Dear Experts,

We are on 12.1.0.2 version

2 node RAC

We are following note id How To Add a New Disk(s) to An Existing Diskgroup on RAC Cluster or Standalone ASM Configuration (Best Practices). (Doc ID 557348.1) to add disks to existing DATA diskgroup.

We are using ASMLIB.Are below steps mandatory to perfrom below step 2 and step 3

2) Confirm the disks are visible (I/O) at OS level (as oracle or grid OS user) from each node:

$> id

$> ls -l <disk name>

$> dd if=<raw/character or block partition device in question> of=/dev/null count=100 bs=8192

Example:

$> dd if=/dev/raw/raw1 of=/dev/null count=100 bs=8192 # raw device