We use a Mac Server in another subnet as a Time Machine target for some of our MacBooks (macOs 10.13). Despite the manual configuration caused by the server being on a different subnet, this setup works quite ok.

I recently configured a new MacBook to backup onto the Mac Server. Now, after some weeks and still without one finished backup, the client starts to complain that the backup volume is running out of space. I checked the Mac Server, but it has 1.6TB left.

I remember that I once configured a quota of 500GB per backup back on the Mac OS X 10.10 server. But with macOS 10.13 and Server 5.6.1, Time Machine is no longer part of the services provided by the Mac Server. If I got it correctly, Time Machine now backs up to a simple SMB share. However, my client still shows:

333 GB of 500 GB available

The question is: Where is this 500 GB coming from? Is this a local setting? Or is the Mac Server still more than just a plain file share when it comes to Time Machine?

And the question behind the question: Is this quota a possible cause for the problem? Or are there other reasons for Time Machine to complain about a full disk, even when it isn't full?

1 Answer 1


There was a Time Machine quota setting in macOS Server. Maybe the quota is still set even after the UI has been removed?

Maybe this URL helps:


If I understand this correctly, the quota is set in a hidden plist file in the root of the Time Machine share.

The Time Machine quota setting in "normal" macOS is in the Sharing preferences. Right-clicking a shared folder has an "Advanced Options…" dialog.

macOS Sharing TimeMachine Quota

There is also a local Time Machine quota setting but I don't know if this is "forwarded" to network shares, probably not.


You can check the local quota (if set) via

defaults read /Library/Preferences/com.apple.TimeMachine MaxSize
  • 1
    Thanks for the descriptive answer. I actually found the hidden plist file on the remote disk, which shows the value from the "Advanced Options..." dialog. However, changing it has no effect. Also, there was no MaxSize in com.apple.TimeMachine. I added it, but, even after some days, haven't seen an effect yet.
    – PVitt
    Commented Oct 5, 2018 at 8:51
  • After quite some time, I noticed a change of the Time Machine quota to the value I saved in the hidden plist-file. So it seems to work, although it needs some time to be discovered.
    – PVitt
    Commented Oct 31, 2018 at 11:00
  • I followed this advice and set "Limit backups to" 300GB, but one of my backups now takes up 747GB. It seems to me that this limit is ignored. Commented Feb 22, 2023 at 21:21

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