A Fresh Install of macOS Sierra

I’ve just finished reinstalling my Mac, completely wiping the drive and starting again. This is just a bit about why, how, and how it turned out.


Well, it had been getting a bit crashy recently, for one thing. Sometimes it just didn’t want to come back from sleep mode (I know the feeling), and I had to power off and start it again. I did a repair on the drive, from the Recovery system, which I’ve done before, and it may be that OS updates will fix problems in future, but it was getting a bit worrying.

I haven’t reinstalled it since getting it, and it’s around three years old now, so it’s had a lot of use, and a few versions of macOS (or OS X pre-Sierra if you’re being pedantic), and quite a lot of things have been installed and removed. It probably had more stuff that I really should have deleted, but hadn’t got around to.

Also, related to all that, it was getting a bit full. There was less than 100Gb of free space on the drive, and macOS reckoned it could clear another 150Gb or so by purging it if things got tight. Not too worryingly short of space, but pretty full for a 1Tb drive.


Easier than you might think. I prepared by doing a fresh backup with Time Machine to a portable drive, which I don’t do nearly as often as I should, then restarted into Recovery mode. To do that, restart (or shut down then switch on), and immediately hold down Cmd-R. Keep it down until the logo appears, or it asks for your password if you’ve set one.

The recovery system appears, and from there I used Disk Utility to remove the Macintosh HD partition, and make a new Mac Extended Journaled partition. The first time, I made it encrypted, but after doing the first part of the install, the machine wouldn’t mount the drive and continue. So I tried without encryption and that worked. Once it’s finished with the installation, one of the first things the on-boarding process does is ask if you want to turn encryption on, so I did it then.

Once iCloud was enabled, things started syncing.

If you have a lot of iCloud data, perhaps including a lot of photos in your iCloud Photo Library, it can take a while to sync afterwards. I have around 80,000 photos, and quite a lot of other data, so I knew it would take some time. This time, I’ve left Photos set to optimise storage, so it won’t download the full-size photos to this machine until they’re needed. I may decide to switch that over later, but for now, I’m going to go with trusting Apple not to lose all my photos, which is a little scary. But it’s almost halloween, so we’re supposed to do scary things.

The Result

I’ve been surprised by how much came back on its own. My mail account was there, but even the rules came back. I had to enable the again, but they were there. My browsing history was intact, synced with iCloud. Even some of my trash seems to have returned, which was unexpected. I’m guessing that one is actually recently deleted items inside Photos and iBooks being shown in Trash as well as in the apps.

A couple of days later, everything still hasn’t synced. I suspect Apple limits how much can sync per day – Photos did so when I was first syncing my library into iCloud, but it seemed to come down pretty easily this time, at least without trying to download all the photos.

So far, things have been ok – nothing much lost that I’ve had to bring back from backup, and it all seems nice and speedy again. The biggest gain is disk space, though. I’ve gone from an almost full 1Tb drive to having over 700Gb free. No crashiness so far, so it seems to have been worth the time and effort.

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