Time Machine over iSCSI

With BeamDisk, a disk on your server can be a Time Machine destination, just like a drive plugged into the Mac.

What you need

BeamDisk on a Mac with Apple Silicon, macOS 27 or later.
An empty disk on your server for this Mac, connected with BeamDisk (Add your first disk). Give it room: Time Machine keeps many versions.
An administrator’s password, to install the profile and to change Time Machine’s settings.

Set it up

Connect an empty disk with BeamDisk, and format it as APFS with Format… if it’s new.
Install the profile. In BeamDisk’s Settings → Time Machine, click Install Profile…, and System Settings opens at Device Management: under Downloaded, double-click “BeamDisk: Time Machine support”, click Install…, then Install, and enter an administrator’s password.
Choose the disk. Click Open Time Machine Settings, click +, and choose the disk.

Time Machine may create its own backup volume on the disk, named after the disk with a number, such as “Backups 1”. Backups then run on Time Machine’s usual schedule.

The Time Machine guide covers restoring and what to expect.

Frequently asked questions

Can Time Machine back up to an iSCSI disk?

Yes, with BeamDisk. After a one-time setup in BeamDisk's settings, the iSCSI disk can be chosen as a Time Machine destination like a disk plugged into the Mac.

How fast is a Time Machine backup over iSCSI?

In BeamDisk's tests on 10 GbE to a TrueNAS SSD pool, the first full backup of a Mac (71.4 GB, 1.8 million files) took 8 minutes 19 seconds, against 9 minutes 39 seconds for the same backup over SMB to the same pool. Later backups copy only what changed; one with 5.8 GB of new files took about a minute either way.

Why does Time Machine ask for an administrator password?

While BeamDisk's Time Machine profile is installed, Time Machine settings ask for an administrator's password before changes.

Can several Macs back up to one iSCSI disk?

No. BeamDisk gives each disk to one Mac at a time, so give every Mac its own disk on the server.