Apple Event: May 7th at 7 am PT
I should know this, but... iMac 21.5, late 2015 (I think). Drive failed, replacing with a drive from OWC. Once I get it installed, how do I get the system bootable again? I don't have a backup from the previous drive, I've already replaced the whole system, so I just want to get this back to factory fresh...
iMac Line (2012 and Later)
Try booting into Recovery Mode using Command + R which should in theory boot into the online macOS installer for the last OS that was used on this iMac. If you want the newest supported OS, then boot into Internet Recovery Mode using Command + Option + R instead. Unfortunately some Macs will only boot into the online installer for the OS which originally shipped with the Mac from the factory. If you have access to another Mac, then you may be able to create a bootable macOS USB installer.
Once you are booted to the macOS installer, you need to properly partition & format the new drive for use with macOS. You will need to launch Disk Utility and erase the whole physical drive as GUID partition and APFS (top option) if you are installing macOS 10.13+, otherwise if you are installing macOS 10.11 to 10.12 you will need to erase the whole physical drive as GUID partition and MacOS Extended (Journaled). After erasing the whole physical drive, then quit Disk Utility and select the "Reinstall macOS" option.
Make sure to always have frequent and regular backups of your computer and all external media (including the cloud) which contains important & unique data.
Try booting into Recovery Mode using Command + R which should in theory boot into the online macOS installer for the last OS that was used on this iMac. If you want the newest supported OS, then boot into Internet Recovery Mode using Command + Option + R instead. Unfortunately some Macs will only boot into the online installer for the OS which originally shipped with the Mac from the factory. If you have access to another Mac, then you may be able to create a bootable macOS USB installer.
Once you are booted to the macOS installer, you need to properly partition & format the new drive for use with macOS. You will need to launch Disk Utility and erase the whole physical drive as GUID partition and APFS (top option) if you are installing macOS 10.13+, otherwise if you are installing macOS 10.11 to 10.12 you will need to erase the whole physical drive as GUID partition and MacOS Extended (Journaled). After erasing the whole physical drive, then quit Disk Utility and select the "Reinstall macOS" option.
Make sure to always have frequent and regular backups of your computer and all external media (including the cloud) which contains important & unique data.
Excellent reply, thank you! I wasn’t sure if recovery mode was on the drive (which has failed) or in firmware. I’ll try all the sources you have suggested. I always keep backups, which I used to set up my new system, but subsequently I’ve modified that backup with the new system, so not sure if it’ll work on the new drive. But you’ve pointed me in the right direction, thanks!
chrisc5a wrote:
Excellent reply, thank you! I wasn’t sure if recovery mode was on the drive (which has failed) or in firmware.
It depends on whether macOS 10.12.6+ was ever installed which would have updated the system firmware with the ability to access the online recovery mode. If macOS 10.12.6+ was never installed, then you won't have access to Internet Recovery Mode and will instead need to use a bootable macOS USB installer (or attempt to access recovery mode from the bad hard drive).
Ok gang, I’m currently waiting for my older iMac to do its online restore thing. Meanwhile, I had purchased a 27” iMac refurb from Woot, and trying to get it up and running. It comes with a third-party wired keyboard and a third-party mouse. I’m having great difficulty getting configured, I’m not used to doing the initial config with only a keyboard. I can get it to the point of asking to agree to the user agreements, but I can’t get past that, accepting the agreement just tells me that the agree button will let me proceed, but it doesn’t. I know this is confusing, but does anyone have any thoughts?
Replaced hard drive, how to make system bootable again?
