my name is Chriz Ott, I'm working with NetApp as a Principal Architect for Transition.
An easy way to get your useable space is using df -A or df -h on the CLI.
Be aware that there is a gap between used capacity and available capacity, because you probably committed "free" capacity to a particular volume by using the volume "space-reserve volume" option.
ONTAP reserves the complete capacity of that volume for future use and it will not show up as available, eventhough it is not used yet.
You can familiarize yourself with the capacity topic here:
hope that helps.
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