Time Machine

Can multiple systems backup to the same partition on the time machine disk?

Yes, if it is a network share. No if it is direct connected.

On a network backup, each computer will create their own Sparsbundle disk image that is independent of the rest of the backups on the share.

If you are going to back up the host onto that device, you would need to create a partition (or APFS Volume) for each direct connected machine. The others can all be in the other Volume/Partition.

Still not getting it to work.

Initially, when you try to mount the share in the Finder, it will attempt to connect using the current logged in user credentials. If it does mount, you have to use Connect As… to switch to the Sharing Only user.

Try forcing the connection with Connect to Server (cmd-K). The connection string will be something like:

smb://sharingUserName@hostname/TMShare/

It should ask for the sharing user password.

If you are trying to connect over the network, on the host machine create a Sharing Only user in Users & Groups System Prefs. Same as any other user, except change the type from Standard to Sharing Only.

In Sharing System Prefs on host, File Sharing, add the drive and add the Sharing Only user with read/write.

Ctrl-click on the share in File Sharing and choose Advanced. Set it as a Time Machine Destination. Make sure you are sharing via SMB (you don’t have to turn on any accounts).

On each client, remove any previous attempts to connect and add the Time Machine drive to each computer. When it asks for authentication, use registered user and put in the Sharing Only username and password.

If you have problems, try connecting to the host in Finder using the Sharing Only user credentials. Once you mount the Time Machine share, try adding it to Time Machine again.

And, delete all of the individual user accounts you created on each Mac and the Host.

cdlvj130 wrote:

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So multiple systems have to have their own volume or partition, Correct?

Each machine needs to have a separate Time Machine Volume. It catalogs all the changes made on a single machine and saves appropriate backup data required for that machine. Time Machine is a single machine based app not a "client/server" paradigm.