Why erase and restore your Mac?

I am a power user. I develop iOS and Mac software. I run betas of my firewall, my operating system, and my applications. I have developer tools installed. I am bound to have problems.

I am not alone though. OS X, over time, can become crufty. Old extensions,old files, or even improper installations. Third party installers often corrupt permissions or install older components.

System crashes (kernel panics) and OS bugs can lead to disk corruption that most do not catch until it is too late. The operating system does a poor job on alerting you if there are file system issues.

Running Disk Utility to repair these issues may seem successful, but sometimes are not. You may notice a “lost + found” folder on the root level of your hard drive. If you find a “iNode” file within that folder, things are not good.

My Late 2013 MacBook Pro is a little over a year old and has gone through many betas, many system crashes, but according to Disk Utility, all was well. I had had disk corruption that needed fixing by booting from the recovery partition, but Disk Utility fixed it.

Come Christmas, I bought a new monitor for myself, a new Razr Naga Mouse (which has its own drivers) and a new USB dock. The computer started to complain.

At first, it was spinning beachballs of death. Then it was strange kernel panics in the file system and in the graphics drivers. Finally I had had enough.

As members of PMUG know, I have many backups. I backup via Time Machine to a drive on my OS X server, to a local WD Passport drive, and to a drive at work. I also have several clones made with Carbon Copy Cloner. One is in the bank, one is at home, one is at work. All are encrypted.

I figured that if i was having all of these issues, I had better restore, because backing up corruption is not good. So I did what I have not done in a very long time.

I erased the disk and started over.

I began by booting from the recovery partition. This is easy, just reboot and hold down COMMAND R. Hold these keys down until the booting process starts, which is a black screen for OS X 10.10 (Yosemite).

Once the recovery tools had booted, I chose Disk Utility and erased my hard drive. Gulp. It was nice knowing you! Because I use FileVault, I had to first unlock the volume by selecting it and choosing Unlock from the File menu. Then I erased it as a normal journaled disk (not encrypted!)

I then quit Disk Utility and used the recovery menu to reinstall OS X Yosemite. This took about 35 minutes to download and install.

Next up was telling OS X that I wanted to restore from a Time Machine backup. I chose my WD Passport as I had just backed up to it and being a USB 3 drive, this was about as fast an option I had. The restoration took about 2.5 hours.

When all was said and done, I got about 30 gigabytes of my drive back. I am hoping this is due to all of the caches, sleep images, and other operating system artifacts, but I am not certain. A quick perusal though my file system seems to have everything I expected.

I suppose that some of my used space was because of previous disk corruptions, or the worst case scenario is that corruption caused some files to never be backed up, or overwritten. Time will tell.

This is why it is also import to archive. An archive is a backup that you then put away forever. Once a year I take one of my external Time Machine drives and label it as an archive. It goes into the bank and then I buy a new 1TB drive.

With this system, if I notice years down the road that I am missing a file I really want, I can go back to an archive and see if it is there.

Both backups and archives are important.

In the end, all spinning beachballs have disappeared. All kernel panics have disappeared. The system is fast and stable. Something was bad, and it seems that only a complete restore was the answer.

TL;DR If you are having very weird Mac problems, consider not just reinstalling OS X, but also erasing the entire machine and doing a full restore from backup.