How to Safely Defrag a Mac’s Hard Drive

Every Mac owner hates seeing an annoying spinning beach ball on the screen. One thing is to see it on the beach in summer, and another thing is to wait endlessly until the chosen app or file launches. It means nothing else than an overall system slowdown. Luckily, Mac users do not have to defrag the computer regularly. Maybe, it will be necessary after ages of usage and regular updates.

Mind that an active FileVault will prevent you from defragging Mac’s hard drive as it is one big, encrypted image.

Anyway, the first thing to do is to back up personal data with the help of Time Machine or some other methods. Do not forget to explore the ‘Fix It’ features because defragging does not always solve all issues in software.

To start with several facts you should know about:

  1. Just hard drives need defragging. No need to do that with solid-state disks (SSD)!
  2. It does not make sense to defrag a hard drive frequently on Mac OS X and macOS.
  3. Due to construction peculiarities, hard disk drives are faster at the start of the drive, and slower at the end. The data is written on the top of the drive first, and then it moves down.
  4. The initial 50% of the drive is quicker than the second half because of the more sectors in every track. Try to place all information in the first 50% of the HD to let it be speedy.
  5. You can re-partition the unnecessary space at any moment and apply it as a backup clone.
  6. Mac OS X / macOS upgrades and daily operations tend to move data on the drive and make it less optimized.
  7. In case of the failing sectors, a user may experience a drop in reading That is when a spinning ball may start to annoy you.

Steps on the way to Defragging Mac’s Hard Drive

  1. To begin with, minimize the user information on the boot drive (start with videos as they are the largest). You should obtain more than 50% of the drive’s capacity. Do not try to defrag a Mac having over 80% of storage occupied because the machine will refuse to start up.
  2. Apply Activity Monitor and restart to notice the modifications.

A blank independently powered external drive should be in place to continue the operation along with the Carbon Copy Cloner. A user needs them to copy the OS X boot partition to the external location with the help of default settings and a complete duplicate.

  1. After that, restart the Apple computer with the help of Option + Alt key down. Start from the copy with the help of Startup Manager. Examine the clone for a while to make sure it is reliable. Try to capture any unfamiliar problems. Usually, there are no issues.
  2. Start up from the clone. Apply Disk Utility to Security Option. Next, Erase with the “Zero” or second secure selection/internal OS X boot partition/entire drive in case no Recovery/Boot Camp partition is in place. “Zero” out all the bits. Once it reads back for confirmation, map off any corrupted sectors during the process. Mind that the failing sectors usually take more time to read.

Important notice: A user will have to do the operation one time per drive, so you may have to Erase Free Space -> Zero probably just one more time another year. Do not move the hard drive or Mac when it is operating!

  1. Once finished, clone the external partition back onto the internal. Move from Disk Utility to the Repair Permissions feature.

This way, it is possible to solve the Boot Camp partition formatting issue, the bad sectors, defragmentation problems, bloated or corrupt caches, and issues with optimization at once. Ensure to have a working backup that you can boot in the process.