ZFS Can Set Quotas on Datasets

I was setting up Arq to back up my Mac to my NAS and realized I didn’t want my backups to eventually consume all available storage. ZFS makes this trivially easy with quotas.

First, create a dedicated dataset for backups:

sudo zfs create my-nas/arq-backups

Then set compression (might as well):

sudo zfs set compression=zstd my-nas/arq-backups

And finally, cap it at 200GB:

sudo zfs set quota=200G my-nas/arq-backups

That’s it. Now Arq sees a 200GB volume and will manage retention accordingly, while my other datasets stay protected from backup bloat.