Looking for advice on the best way to reformat my SSD and start all over with my Mac.

I've got an iMac (Retina 5K, 27-inch, 2017) whose operating system has been upgraded every year for about five years. For the past several months, I've been seeing crashes on shutdown, error messages on startup that say "the Mac shut down because of a problem" even though it seemed to shut down fine, disk errors when running Disk Utility in Recovery mode, occasional random crashes (not many), etc.

There's been no data loss so far but it feels like it's time for a fresh start. I'm aware these could be signs of impending drive failure but I would like to reformat the drive and see if it clears things up before I go the route of buying new hardware.

From what I've read, I'm considering creating a bootable USB installer and then wiping the internal drive clean with it. Hopefully I can "fix" any bad sectors by writing to every block?

Any advice on the best way to do this would be appreciated—as would any advice on other strategies to address these problems. Thanks in advance.

  • 4
    Why not reinstall from the recovery drive. That can wipe all the rest of the SSD
    – mmmmmm
    Commented Jun 17, 2021 at 11:08
  • 1
    You don't need to write to every sector to fix bad blocks. They are mapped out on the fly whenever the drive's firmware finds one. Until the error rate spirals or SMART data indicates potential failure, no other user action is required. 'Disk errors' don't necessarily mean a failing drive [though they may] but a corrupt file system.
    – Tetsujin
    Commented Jun 17, 2021 at 11:44
  • @mmmmmm If it's as simple as that then I'm all for it. Would give me a new container on the disk with a system volume and a data volume? And then I would restore from a Time Machine backup?
    – Khoi Vinh
    Commented Jun 17, 2021 at 13:32
  • @Tetsujin Thanks for the insight. I'm assuming you'd endorse mmmmmm's advice then?
    – Khoi Vinh
    Commented Jun 17, 2021 at 13:34
  • 1
    Yes - I've never actually done it on Big Sur, but yes, you should be able wipe & reinstall from Recovery or at worst, Internet Recovery; then migrate
    – Tetsujin
    Commented Jun 17, 2021 at 14:18


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