I have two macs running OS X 10.10.3. One has Server.app installed, is connected to the internet via ethernet, and also has a 2 TB disk attached via USB, with two partitions - "Backup" and "Storage". My other mac is a laptop used for schoolwork.

Using the Time Machine feature of Server.app, I was able to use the standard Time Machine interface to begin backing up my local mac onto the "Backup" volume on the server mac over the network.

However, I discovered that it takes 7 minutes to copy a 1 GB file over AFP, so backing up 300 GB on my local mac would take at least 35 hours.

So, I'm trying to figure out a way in which I could do the initial 300GB backup onto "Backup" over USB, and then connect that external hard drive to the server mac and continue doing backups over the network. That way, the incremental network backups would be much smaller than 300GB and could be done in a reasonable time period, e.g. overnight.

Any suggestions? I read the man page for tmutil but I'm not very comfortable with it just yet.

  • Sounds like curing symptoms. With a decent switch, at least cat5 ethernet cables and proper network settings you should get ~30 MByte/s or better (depends on the USB-interface, the disk to backup and the external disk). So better check your settings and cables.
    – klanomath
    Apr 22, 2015 at 17:46
  • I'm not the administrator of my network, so I can't modify the network infrastructure or settings, unfortunately.
    – user102656
    Apr 22, 2015 at 21:03

1 Answer 1


This MacSales article covers how to do this very well:


Essentially, you start with a fresh Time Machine backup. Start it on Wifi, then stop it, as it begins to backup files. This basically establishes the Time Machine archive. Then you attach your hard drive (or laptop) to the wired network, and resume backup. Once you have the initial backup done over the much faster wired network, subsequent backups will be much faster, as the are much smaller.

You establish the initial Backup over wifi because Time Machine does things differently over wifi vs directly connected.

In any case, best of luck to you: I have never managed to get Time Machine to work reliably over wifi, and especially if you tend allow your Mac to go to sleep during a Time Machine backup (shut the lid for example)

  • This doesn't work in Mojave — when "Back up now" is selected with the USB drive directly attached, it looks for the network location and then complains it isn't available.
    – Cai
    Jan 19, 2019 at 14:27

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