In Clustered Data ONTAP we can issue systemshell commands from the cluster shell at the diag priviledge level. So adding disks only takes 3 commands:
systemshell local "cd /sim/dev;sudo vsim_makedisks -t 35 -n 14 -a 2"
In this example, I've added 14 (-n 14) 500MB SSDs (-t 35) on adapter 2 (-a 2). There are 4 adapters numbered 0-3, but 0 and 1 are fully populated by default. That leaves adapters 2 & 3 available for more disks or SSDs, each of which can take up to 14 disks.
If your simulated cluster has more than one node, replace 'local' with '-node <node name>' to make sure the disks are created on the correct node.
To get a list of valid disk types:
systemshell local vsim_makedisks -h
The reboot is inconvenient, but avoidable. Hot adding disks takes a few more steps. More on that later.