partition troubles

[silentearth]

Hello all, I’m looking for assistance with my iMac that I’ve been trying to get ready to list on the market, however I tried accessing Disc Utility from the boot menu with a wireless Windows keyboard (holding down the Alt key which is equivalent to the option key on the Apple keyboards) but it would always take me to the login screen instead of OS utilities. So, I decided to partition the drive in half, do a clean install of OS on one half, then erase the other half with my data on it and have just the new partition with the clean install on it. Unfortunately I can’t erase the original partition, so I went out and bought a wired Windows keyboard and tried again to access OS utilities, this time it worked, so I erased everything on my hard drive (Macintosh HD) and tried going back to the original partition so I could do a clean install of the OS on that like I originally wanted to, however after accessing disk utility from OS utilities after wiping my HD, I now have “free space” partitions that I didn’t create, and I can’t remove them or resize Macintosh HD. When I try to install the OS anyway, it says I no longer have enough space to install. Here’s the step-by-step process of me trying to go back to a single partition: (excuse the quality of the pictures)

 

[chscag]

Boot the machine from a macOS external bootable hard drive or another Mac in target disk mode and wipe the hard drive. Then start over. When preparing a machine to sell you should always have an installer on hand to use to wipe the machine, install a clean copy of macOS, and then leave it for the buyer to create a new account.

 

[silentearth]

I do have a disc image of High Sierra (what was on it before I wiped it) on a 16GB flash drive, however it’s not showing up in the boot menu so I’m assuming it’s not a bootable drive. I have another iMac I can use for the target disc mode I’ll just need to pick up a thunderbolt cable to do so. Thank you!

Boot the machine from a macOS external bootable hard drive or another Mac in target disk mode and wipe the hard drive. Then start over. When preparing a machine to sell you should always have an installer on hand to use to wipe the machine, install a clean copy of macOS, and then leave it for the buyer to create a new account.

 

[spooklog]

If the flash drive is properly configured, it should be bootable. Use the Mac's Startup Manager (hold down the option key when starting the machine) to display all the bootable drives. More details from Apple Support: https://goo.gl/zlnZLS

 

[silentearth]

How would I go about a making the flash drive bootable? I’m assuming it’s currently not since startup manager only shows this:

If the flash drive is properly configured, it should be bootable. Use the Mac's Startup Manager (hold down the option key when starting the machine) to display all the bootable drives. More details from Apple Support: https://goo.gl/zlnZLS

 

[spooklog]

Creating a bootable flash drive isn't a problem. This link explains one way to do it. https://goo.gl/USMhX7

 

[silentearth]

Tutorial worked, thanks! However after selecting to boot from the installer it brought me to OS Utilities after waiting on the load screen for a bit. Selected “Install macOS upgrade or install” and I have these two options, the installer drive and my hard drive. Still can’t figure out how to reverse my partitioning back to a single 1TB partition, and the installer said the 6GB available on my iMac’s hard drive isn’t enough room.

Creating a bootable flash drive isn't a problem. This link explains one way to do it. https://goo.gl/USMhX7

 

[chscag]

Again.. you need to boot from a bootable flash drive or another Mac via target mode, use Disk Utility and wipe the hard drive. Then.. you can use the installer to install High Sierra. You're getting ahead of yourself. You can't do it the way you're attempting.

 

[silentearth]

My apologies, I assumed I could just install from the flash drive and be all set, but nothing is ever that easy lol
Booted from the flash drive again and selected disk utility and clicked on my HD and erased it successfully, however it still says my HD is 6GB with 994GB if free space. Then I tried hitting the restore button and restored it with the bootable drive to see if maybe that would fix it, but I got the error message, “restore process failed, not enough space to restore”
So then I tried removing the “free space” partition, but got another error message, “the requested size change for that target disk or a related disk is too small. Please try a different disk or partition, or make a larger change.”

If purchasing a thunderbolt cable and whiping the hard drive through target mode will be easier, I may be better off doing that.

Again.. you need to boot from a bootable flash drive or another Mac via target mode, use Disk Utility and wipe the hard drive. Then.. you can use the installer to install High Sierra. You're getting ahead of yourself. You can't do it the way you're attempting.

 

[DeltaMac]

In Disk Utility - if you erase the drive, which is the partition labeled "Macintosh HD" on your system, that will erase THAT drive, using the space that is already allocated to THAT partition, which seems to be 6GB.
As you appear to need more space than that (and I completely agree with that idea ), then rather than erasing the Macintosh HD, erase the drive itself (the device) which will use ALL available space on the device - and you will have all your space (1TB).
Here's a few simple steps that SHOULD give you a better result.
Boot to your installer drive. Open Disk Utility. Make sure that Show All Devices is selected in the View menu of your Disk Utility.
Choose the top item in the list (NOT Macintosh HD), which should show the manufacturer's description of your drive. I think yours will show "WDC WD10EZEX 00RAKKA0 Media". THAT'S the line that you want to select. NOW, click Erase. Name the drive (Macintosh HD would be OK), choose the format "MacOS Extended (Journaled)", and the Scheme should be "GUID".
Finally, click the Erase button again.
The erase will take only a few seconds.
Quit Disk Utility, which will take you back to the Utilities menu.
Reinstall macOS - choosing the Macintosh HD as the destination. It now will have enough space, and should work this time

 

[silentearth]

Ah-ha! For some reason I didn’t even bother to try looking for the main hard drive, (last time I had to reset an iMac it automatically showed both drives). Silly me. Now I see my actual hard drive of 1TB. The erase worked! Now it’s showing Macintosh HD as 1TB phew, thank you!

In Disk Utility - if you erase the drive, which is the partition labeled "Macintosh HD" on your system, that will erase THAT drive, using the space that is already allocated to THAT partition, which seems to be 6GB.
As you appear to need more space than that (and I completely agree with that idea ), then rather than erasing the Macintosh HD, erase the drive itself (the device) which will use ALL available space on the device - and you will have all your space (1TB).
Here's a few simple steps that SHOULD give you a better result.
Boot to your installer drive. Open Disk Utility. Make sure that Show All Devices is selected in the View menu of your Disk Utility.
Choose the top item in the list (NOT Macintosh HD), which should show the manufacturer's description of your drive. I think yours will show "WDC WD10EZEX 00RAKKA0 Media". THAT'S the line that you want to select. NOW, click Erase. Name the drive (Macintosh HD would be OK), choose the format "MacOS Extended (Journaled)", and the Scheme should be "GUID".
Finally, click the Erase button again.
The erase will take only a few seconds.
Quit Disk Utility, which will take you back to the Utilities menu.
Reinstall macOS - choosing the Macintosh HD as the destination. It now will have enough space, and should work this time

 

[DeltaMac]

Glad to help.
The default for Disk Utility in High Sierra is to show partitions only, and not the hardware device, so that menu item changes how drives are displayed in the list.
I think that is current, because, with most drives in Macs being SSDs, High Sierra changes the format in those so the volumes are mostly virtual volumes. It gets a bit confusing when you see a list of ALL volumes, so Apple chooses to make only active volumes as the default (and not devices). It's not always what YOU need to see to setup the drive.

Good luck with selling your Mac!