iMac Capacity

Oh I got it and let me erase it first and covert to guid partition map.

Same problem. Does the article related to this article? https://discussions.apple.com/thread/5812340?answerId=24588944022#24588944022

/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 Mac HD 279.6 GB disk0s2

3: Apple_Boot Recovery HD 220.3 GB disk0s3

/dev/disk1 (external, physical):

#: TYPE NAME SIZE IDENTIFIER

0: FDisk_partition_scheme *15.5 GB disk1

1: DOS_FAT_32 UNTITLED 15.5 GB disk1s1

/dev/disk2 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: VISTA_SP1_HOMEPREMIUM *4.5 GB disk2

Macs-iMac:~ mac$ diskutil cs list

No CoreStorage logical volume groups found

I've tried do internet recovery, it does not help anything wipe completely on iMac and restore factory settings where it should be fresh start. I read the article about how to fix these disks if I have windows disc; goes to data management on windows installer to remove disks and replace something with the disks? However i'm not sure because I didn't want make it worse into dead iMac but I need your help. many thanks.

I do not have the Time machine backup, but I will create backup with my USB after my iMac have been fixed. I do not understand how to do erase the entire outermost disk, I'm not that good technology and prepare easy step by steps?

Macs-iMac:~ mac$ diskutil eraseDisk disk0

Usage: diskutil eraseDisk format name [APM[Format]|MBR[Format]|GPT[Format]]

MountPoint|DiskIdentifier|DeviceNode

Completely erase an existing whole disk. All volumes on this disk will be

destroyed. Ownership of the affected disk is required.

Format is the specific file system name you want to erase it as (HFS+, etc.).

Name is the (new) volume name (subject to file system naming restrictions),

or can be specified as %noformat% to skip initialization (newfs).

You cannot erase the boot disk.

Example: diskutil eraseDisk JHFS+ UntitledUFS disk3

What can I do next?

Macs-iMac:~ mac$ diskutil unmount disk0

disk0 was already unmounted or it has a partitioning scheme so use "diskutil unmountDisk" instead

Macs-iMac:~ mac$ diskutil unmountDisk

Usage: diskutil u[n]mountDisk [force] MountPoint|DiskIdentifier|DeviceNode

Attempt to unmount the directly-mountable volumes on all of a whole disk's

partitions as well as all virtual volumes which are implied by storage systems

such as AppleRAID, CoreStorage, and APFS. If you specify a partition, then that

partition's whole-disk parent is assumed.

Macs-iMac:~ mac$

This forum will keep open while I'm doing these recovery? I have ethernet plug in on iMac. If I did that commands after restart iMac, how would I know which erase the disks? I don't know how to get through to fresh start.

Ok I’m on MacOS Utilities, do I have reinstall macOS? They are locked. I don’t know which I should go first. I’m on disk Utility, there one internal as mac hd. And disk images are OSX base System.

*update, I did expand view and there is media disk. What I can do?

i use internet browser on start up settings and here the output

-bash-3.2# diskutil eraseVolume jhfs+ "REC" disk0s3

Started erase on disk0s3 Recovery HD

Unmounting disk

Dissented by PID=0 (kernel)

Error: -69888: Couldn't unmount disk

I'm not sure what to do next. I saw on Disk Utility and I have REC on list of internal, where theres pink along with blue Macintosh HD on ST3500418AS Media. Sorry, its my first time doing these technology stuffs to resolve the issues on my iMac.

I took your command to run diskutil eraseVolume jhfs+ "REC" disk0s3. I got Rec internal after terminal. I opened up the Disk Utility and click first aid on ST3500418AS Media and it gives me error "First Aid found corruption that needs to be repaired. To repair the startup volume, run First Aid from Recovery. Click Done to continue."

Checking prerequisites

Checking the partition list

Checking the partition map size

Checking for an EFI system partition

Checking the EFI system partition’s size

Checking the EFI system partition’s file system

Checking the EFI system partition’s folder content

Checking all HFS data partition loader spaces

Volume Macintosh HD on disk0s2 has 0 bytes of trailing loader space and it needs 134,217,728 bytes

Problems were found with the partition map which might prevent booting

Operation successful.

I cannot go forward without error and simple steps to fix issue, Ive been exhausting and lots of patiently to fix on my iMac and sitting hours, idle my processes on iMac desktop and I tried to figure out whats wrong with my capacity excepting wait to get these fix done. because I'm not that great technology to fix my iMac because they're complex codes to fix on computer. I wouldn't worry about my iMac if I back it up by my usb after getting back 500gb like fresh start. I'm sorry. I have the anxiety with me because of this Mac is expensive computer I've ever got. Thanks. These issues I got because I'm trying to install windows 7 or something on my iMac, none of these continue my process to install windows but it is only for after fix the capacity issue first and I would not understand the steps to set up windows from bootcamp/usb installer.

thank you. this has solved my capacity issue. Im on fresh desktop, I would like to install windows on my iMac and how do I do it?

here is my iMac info

Mac (21.5-inch, Mid 2010)

Processor 3.06 GHz Intel Core i3

Memory 4 GB 1333 MHz DDR3

Graphics ATI Radeon HD 4670 256 MB

Serial Number W8*****DAS

<Personal Information Edited by Host>

Model Name: iMac

I do not have a physical dvd to install Windows. I have USB with me, is there a way can I create bootable installer for it to install windows 7 or etc on iMac and how to set up with usb steps? I do not know how too.