# Back up with Time Machine

> Use an iSCSI disk on your server as a Time Machine destination with BeamDisk: format an empty disk, install BeamDisk's Time Machine profile once in Device Management, and choose the disk. With measured backup times.

With BeamDisk, an iSCSI disk on your server can be a Time Machine destination, like a drive plugged into the Mac. Setting it up takes a one-time profile that lets Time Machine use disks connected by BeamDisk, approved by an administrator.

## Before you start

- Connect a disk for this Mac's backups with BeamDisk ([Add your first disk](https://beamdisk.app/docs/getting-started/add-a-disk/)). Give it plenty of room: Time Machine keeps hourly, daily and weekly backups.
- Give each Mac its own disk: BeamDisk gives a disk to [one Mac at a time](https://beamdisk.app/docs/disks/exclusive-access/).
- You need an administrator's password to install the profile, and again whenever you change Time Machine's settings while it's installed.

## Set it up

BeamDisk's Settings → Time Machine sets out the same three steps, with a status at the top: **Profile not installed**, **Waiting for your approval in System Settings since** a time, or **Configuration profile installed**.

1. Format the disk with **Format…** on its page (or use an empty APFS disk). See [Format a new disk](https://beamdisk.app/docs/disks/format/).
2. In BeamDisk's Settings → Time Machine, click **Install Profile…**, and System Settings opens at General → Device Management.
3. Under **Downloaded**, double-click **BeamDisk: Time Machine support**.
4. Click **Install…**, then **Install** to confirm, and enter your password when macOS asks. Back in BeamDisk, the step reads **Installed**.
5. Click **Open Time Machine Settings**. Click **+**, choose the disk, and confirm.

The first backup copies everything; later ones copy only what changed. Time Machine may create its own backup volume on the disk, named after the disk with a number, such as "Backups 1".

> **The profile isn't under Downloaded?**
>
> macOS removes a downloaded profile that isn't installed after a while. While BeamDisk waits for your approval, its Settings show **Finish in System Settings** with an **Open Device Management** button, which hands the profile over again and opens the pane.

## How fast

Measured on 10 GbE to a TrueNAS SSD pool, with the same Mac backing up the same data minutes apart:

| Backup | Over BeamDisk | Over SMB, same pool |
|---|---|---|
| First full backup: 71.4 GB, 1.8 million files | **8 min 19 s** | 9 min 39 s |
| Later backup: 5.8 GB of new files | 67 s | 72 s |

Later backups take about the same time either way: a repeat of that one took 65 s over BeamDisk and 63 s over SMB. Time Machine itself sets the pace: its work on each file, not the network, decides how fast a backup goes, so even on 10 GbE most backups run well below the network's speed. Large files copy at close to network speed over either. The [benchmarks](https://beamdisk.app/benchmarks/#time-machine) replay both full backups.

## Restore files

Restore files the usual way, from Time Machine in the menu bar, with the backup disk connected in BeamDisk.

macOS Recovery has no iSCSI initiator, so it can't reach a backup on a BeamDisk disk. Plan whole-Mac recovery with that in mind.

## Good to know

- **Administrator password.** While BeamDisk's Time Machine profile is installed, Time Machine settings ask for an administrator's password before changes.
- **Spotlight** stays on for the backup disk: Time Machine needs it. See [Spotlight on a disk](https://beamdisk.app/docs/disks/spotlight/).
- **Test Speed** can't test a backup disk: macOS lets no app write test files there.
- **Erasing.** Erase and Reformat… warns when a disk holds Time Machine backups, and Time Machine then has to be set up for that disk again.

## Stop using Time Machine with BeamDisk

Remove the disk from Time Machine's backup disks, then remove **BeamDisk: Time Machine support** in System Settings → General → Device Management.