Apple Boot Recovery (disk0s3) is 220GB, but the correct size is supposed to be 650MB. This is a known issue with High Sierra.
Assuming you have Time Machine backup of macOS, boot into Internet Recovery, and erase the entire outermost disk in Disk Utility, or alternatively (and my preferred method), click on Utilities -> Terminal, and run
diskutil eraseDisk disk0
In Disk Utility, do you see a 'Macintosh HD' and an outer disk which contains 'Macintosh HD'? If yes, click on the outer disk and click on erase. Alternatively, we can use the command-line method.
KristopherWaite wrote:
It does not restore the capacity.
It will not. Notice that you are erasing disk0s2 (260GB), not disk0 (500GB). You need to erase the outer ST (Seagate) disk.
Click on the line which has the 'ST3500418AS Media', and in the right-hand pane, you should see an 'Erase' button. Click on the 'Erase' and check the output.
Since we can erase the Recovery disk, now run
diskutil mergePartitions jhfs+ "Macintosh HD" disk0s2 disk0s3
The order of disks is critical, otherwise you will lose data. Post the output of the command.
You will need to erase the ST entry, not Macintosh HD, and re-install macOS from beginning. We can continue the discussion here.
I believe my iMac is in serious condition, Ive been tried looking for all forums about my issues. This is only last forum I would get a help from the apple communities.
here the output.
Last login: Tue Nov 7 10:31:35 on console
Macs-iMac:~ mac$ diskutil list
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *500.1 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_HFS Macintosh HD 279.6 GB disk0s2
3: Apple_Boot Recovery HD 220.3 GB disk0s3
Macs-iMac:~ mac$ diskutil cs list
No CoreStorage logical volume groups found
Can you install macOS on an external disk - How to reinstall macOS - Apple Support ? It will allow us to check if the internal disk may be failing.
Please run
diskutil eraseVolume jhfs+ "REC" disk0s3
Click on Done, click on 'Macintosh HD' and check the Mount button, unmount if necessary, and retry the erase on the ST media.
Macs-iMac:~ mac$ diskutil eraseVolume jhfs+ "REC" disk0s3
Started erase on disk0s3 Recovery HD
Unmounting disk
Erasing
Initialized /dev/rdisk0s3 as a 205 GB case-insensitive HFS Plus volume with a 24576k journal
Mounting disk
Finished erase on disk0s3 REC
Macs-iMac:~ mac$
No, you cannot use a USB, because it does not work correctly.
Download the official ISO from Microsoft's Software Download . Right-click-click on the ISO, insert a blank DVD-R Single Layer disc, choose Burn, expand the Burn dialog, check Verify and Mount options and burn the ISO to the DVD. Run BC Assistant, and click on the last option - Install - and follow prompts.
If you are in the US, see Amazon.com: Verbatim 4.7GB up to 16x Branded Recordable Disc DVD-R 100-Disc Spindle 95102: Home Audio & Theater . Look for these on Amazon locally or any local computer store should carry these.
Assuming you are in Internet Recovery, run
diskutil unmount disk0
If you get an error with 'Device Busy', then you are most likely in Local Recovery.
Try
diskutil unmountdisk disk0
iMac Capacity
