I have an older, late 2012 model, Mac Mini that has gone through quite a few operating system (OS) upgrades over the years and has gotten progressively slower each time. In an attempt to regain some of this lost speed I decided that I would erase the drive and do a clean re-install of the OS. My plan of attack was as follows:
- Do one final upgrade OS upgrade in order to move from the installed OS X El Capitan to the newly released macOS Sierra.
- Use the newly upgraded recovery partition to erase the drive and re-install the OS.
My troubles first began when I attempted to upgrade to macOS Sierra from the Mac App Store in El Capitan. The download was taking ages and even timed out displaying an error message a number of times. Thankfully after doing a little Google searching I discovered that this was a somewhat common issue and is caused either by a bad CDN or a conflict with DNS or… OK no one really knows for sure. In any event the work around was as simple as manually defining my two DNS servers to be 126.96.36.199 and 188.8.131.52. I have no idea why this would make a difference but boy did it ever. The download finished minutes later and I was done the upgrade install shortly thereafter.
Next I restarted the computer and went into recovery mode. Using Disk Utility I blew away the drive’s data and then went back to the recovery mode window to begin the re-install. Unfortunately the very same issue I experienced during my initial upgrade attempt came back to haunt me for the re-install. Worse yet the recovery mode only supports DHCP so you cannot manually set an IP address or DNS servers (yes I tried networksetup from a terminal, it didn’t exist in recovery mode).
The way I worked around this is one part ridiculous and one part… let’s go with genius? Plugging my laptop into my switch via ethernet I manually set my DNS settings to the ones listed above and created a wireless access point so that my Mac Mini could connect to it. This allowed the Mac Mini to still be dumb and only use DHCP but because I had manually set the correct DNS settings on the laptop the Mac Mini would inherit this as well. Believe it or not this actually did work and the download was eventually successful, albeit a fair bit slower than downloading directly.
Of course it must be said that all of this nonsense could have been avoided had
- The download “just worked” and not required me to set a specific DNS in the first place and
- The recovery partition allow me to actually set DNS manually
Oh and so far the Mac Mini does seem faster. So at least there’s that.