1) Ensure your network drive is mounted

2) Find the name of your computer on the network – Open System Preferences – Click the Sharing Icon – The computer name is shown below the input field with .local suffix which should be ignored. ie bretts-macbook-pro.local so computer name is ‘bretts-macbook-pro’

3) Ensure Time Machine will show your NAS device – Click Go and then Utilities – Click the Terminal icon – Type ‘defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1’ and press enter

4) Find the MAC address of your computer – Type ifconfig en0 | grep ether and press enter. Your MAC address is the 17-character string consisting of six pairs of hexadecimal digits separated by colons

5) Create the sparse bundle – Type ‘hdiutil create -size 100g -fs HFS+J -volname “Time Machine” NAME_XXXXXXXXXXXX.sparsebundle’ and press enter, where NAME is the name of your computer on the network (as determined in step 2c) and XXXXXXXXXX is your MAC address (as determined in step 4a) without the colons. Ths will create a 100 gigabyte sparse bundle; to create a sparse bundle of a different size replace 100g with a different value. Do this in the directory on the network drive where you wish to save your backups. 6) Tell Time Machine to use the Disk Image – ‘sudo tmutil setdestination /Volumes/{mounted-disk-image}’ Be sure to replace {mounted-disk-image} with the appropriate name for your new disk image. You will be prompted for your password, this is normal.