Give free space back to the server

On a thin-provisioned volume, such as a sparse zvol on TrueNAS, a disk only uses as much space on the server as has been written to it. Deleting files on the Mac doesn’t tell the server on its own, so the space stays used there until it’s given back.

BeamDisk gives it back on APFS disks:

• Automatically, when the disk connects.
• After it formats a disk, for whatever the disk held before, and after Test Speed, for its test files.
• Whenever you like, with Reclaim Free Space. The disk stays in use while it runs.

Reclaim free space now

1. Open the disk’s page in BeamDisk’s window.
2. Click Reclaim Free Space, under Free space on the server in the Disk card, or choose it from the disk’s Options menu.

While it runs, the card says Giving free space back to the server…; then it says when it finished, and what happened:

• Gave 1.2 GB of free space back to the server.
• Nothing to give back: the server already has this disk’s free space.
• Space from files deleted moments ago may not be released by macOS yet, or may be left for a later run. The card says so, and that space goes back at a later reclaim.

Good to know

• Your server needs thin provisioning and support for giving space back (SCSI UNMAP). TrueNAS has both on a sparse zvol.
• Mac OS Extended and exFAT disks don’t give space back yet.
• A snapshot on the server keeps the space it refers to until the snapshot is deleted, whatever BeamDisk gives back.