Mac – Why does “diskutil eraseVolume …” add an extra “Apple_Free” partition

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My question is about why "diskutil eraseVolume" adds an extra partition to an APM partition table.

A little history will help understand the situation better I think — had a 240GB APM style disk on an old PowerBook system that I wanted to upgrade to a larger disk. The PowerBook has some heat related problems and the video goes bad after about 1-2 hours, so wanted to do all this work on another Mac that runs High Sierra, in case the video went bad during the reconstruction on the old PowerBook.

So, basically used "dd" command to clone the entire old 240GB disk to the new 500GB disk, then modified the partition table to correct the total size of disk and size of last partition to compensate for the larger disk, knowing that would need to erase that last HFS+ partition as it's no longer valid. But first, wanted to use "diskutil verifyVolume …" command to check all the various filesystems and discovered that besides the last MacOS volume the xxxxx volume was also no longer correct.

So, no problem I think — will erase the last two volumes and restore from a backup image and all should be fine. Here is what the partition table started out as on the 500GB disk:

==================================pdisk "p" command output============
Partition map (with 512 byte blocks) on '/dev/rdisk6'
 #:                type name               length   base      ( size )
 1: Apple_partition_map Apple                  63 @ 1        
 2:      Apple_Driver43*Macintosh              56 @ 64       
 3:      Apple_Driver43*Macintosh              56 @ 120      
 4:    Apple_Driver_ATA*Macintosh              56 @ 176      
 5:    Apple_Driver_ATA*Macintosh              56 @ 232      
 6:      Apple_FWDriver Macintosh             512 @ 288      
 7:  Apple_Driver_IOKit Macintosh             512 @ 800      
 8:       Apple_Patches Patch Partition       512 @ 1312     
 9:           Apple_HFS MacOS 10.0       64039712 @ 1824      ( 30.5G)
10:           Apple_HFS MacOS 10.1       64039712 @ 64041536  ( 30.5G)
11:           Apple_HFS MacOS 10.2       64039712 @ 128081248 ( 30.5G)
12:           Apple_HFS MacOS 10.3       64039712 @ 192120960 ( 30.5G)
13:           Apple_HFS MacOS 10.4       64039712 @ 256160672 ( 30.5G)
14:           Apple_HFS xxxxx            64039712 @ 320200384 ( 30.5G)
15:           Apple_HFS MacOS           592532992 @ 384240096 (282.5G)
16:          Apple_Free Extra                  80 @ 976773088

Device block size=512, Number of Blocks=976773168 (465.8G)
DeviceType=0x0, DeviceId=0x0
Drivers-
1:  23 @ 64, type=0x1
2:  36 @ 120, type=0xffff
3:  21 @ 176, type=0x701
4:  34 @ 232, type=0xf8ff
======================================================================

I used the command "diskutil eraseVolume HFS+ xxxxx /dev/rdisk6s14" (can't use the GUI Disk Utility program to erase an HFS+, non-journaled, filesystem as that is apparently no longer supported on High Sierra version of Disk Utility.app GUI application) and the partition table had been modified to include a new "Apple_Free" partition right before the "xxxxx" partition:

==================================pdisk "p" command output===========================
Partition map (with 512 byte blocks) on '/dev/disk6'
 #:                type name               length   base      ( size )
 1: Apple_partition_map Apple                  63 @ 1        
 2:      Apple_Driver43*Macintosh              56 @ 64       
 3:      Apple_Driver43*Macintosh              56 @ 120      
 4:    Apple_Driver_ATA*Macintosh              56 @ 176      
 5:    Apple_Driver_ATA*Macintosh              56 @ 232      
 6:      Apple_FWDriver Macintosh             512 @ 288      
 7:  Apple_Driver_IOKit Macintosh             512 @ 800      
 8:       Apple_Patches Patch Partition       512 @ 1312     
 9:           Apple_HFS MacOS 10.0       64039712 @ 1824      ( 30.5G)
10:           Apple_HFS MacOS 10.1       64039712 @ 64041536  ( 30.5G)
11:           Apple_HFS MacOS 10.2       64039712 @ 128081248 ( 30.5G)
12:           Apple_HFS MacOS 10.3       64039712 @ 192120960 ( 30.5G)
13:           Apple_HFS MacOS 10.4       64039712 @ 256160672 ( 30.5G)
14:          Apple_Free                    262144 @ 320200384 (128.0M)
15:           Apple_HFS xxxxx            63777568 @ 320462528 ( 30.4G)
16:           Apple_HFS MacOS           592532992 @ 384240096 (282.5G)
17:          Apple_Free                        80 @ 976773088

Device block size=512, Number of Blocks=976773168 (465.8G)
DeviceType=0x0, DeviceId=0x0
Drivers-
1:  23 @ 64, type=0x1
2:  36 @ 120, type=0xffff
3:  21 @ 176, type=0x701
4:  34 @ 232, type=0xf8ff
===============================================================================

So, why the new "Apple_Free" partition right before the real "xxxxx" HFS+ partition? I did the "diskutil eraseVolume" once more for the MacOS partition and it again created a new "Apple_Free" partition of same size (262144 blocks) before the real HFS+ partition. So that after these two "eraseVolume" commands the partition table now looks like this:

==========================pdisk "p" command output=====================
Partition map (with 512 byte blocks) on '/dev/disk6'
 #:                type name               length   base      ( size )
 1: Apple_partition_map Apple                  63 @ 1        
 2:      Apple_Driver43*Macintosh              56 @ 64       
 3:      Apple_Driver43*Macintosh              56 @ 120      
 4:    Apple_Driver_ATA*Macintosh              56 @ 176      
 5:    Apple_Driver_ATA*Macintosh              56 @ 232      
 6:      Apple_FWDriver Macintosh             512 @ 288      
 7:  Apple_Driver_IOKit Macintosh             512 @ 800      
 8:       Apple_Patches Patch Partition       512 @ 1312     
 9:           Apple_HFS MacOS 10.0       64039712 @ 1824      ( 30.5G)
10:           Apple_HFS MacOS 10.1       64039712 @ 64041536  ( 30.5G)
11:           Apple_HFS MacOS 10.2       64039712 @ 128081248 ( 30.5G)
12:           Apple_HFS MacOS 10.3       64039712 @ 192120960 ( 30.5G)
13:           Apple_HFS MacOS 10.4       64039712 @ 256160672 ( 30.5G)
14:          Apple_Free                    262144 @ 320200384 (128.0M)
15:           Apple_HFS Titoonium        63777568 @ 320462528 ( 30.4G)
16:          Apple_Free                    262144 @ 384240096 (128.0M)
17:           Apple_HFS MacOS           592270848 @ 384502240 (282.4G)
18:          Apple_Free                        80 @ 976773088

Device block size=512, Number of Blocks=976773168 (465.8G)
DeviceType=0x0, DeviceId=0x0
Drivers-
1:  23 @ 64, type=0x1
2:  36 @ 120, type=0xffff
3:  21 @ 176, type=0x701
4:  34 @ 232, type=0xf8ff
=======================================================================

Any idea why these "Apple_Free" partitions get created, or even better how to keep it from happening? Thanks…

Best Answer

Instead of diskutil, try using newfs_hfs to create the filesystems. I don't know what happens in Mac OS, but in my experience, the newfs_* commands in BSD create a filesystem in a partition without changing the partition map.

I don't know why Apple likes to reserve 128 megabytes of free space before an HFS partition. I saw this in my PowerBook G4, when I used the Disk Utility from Mac OS X 10.4 to format my internal hard disk, and it put 128M of Apple_Free (partition 2) between the Apple_partition_map (partition 1) and my Apple_HFS (partition 3). I guess that one can use part of the 128M to add Mac OS 9 drivers for the disk.

Your disk already has Mac OS 9 drivers (Apple_*Driver* and Apple_Patches), so I don't know why it would need 128M of Apple_Free. I speculate that your disk might have IDE drivers but not FireWire drivers. If you would boot your PowerBook in FireWire disk mode, and connect it to some Mac OS 9 machine, then you might need some Apple_Free space to add more drivers; but I never had FireWire hard disks, so I don't know.

Related Solutions

Have /Volumes/Storage Drive

Chances are, it's just a folder created randomly by some app or another at some point to use as a mount point and it was never deleted. It should be perfectly safe to rm -rf it, especially if it is empty.

Note: If you rm -rf in /Volumes, make sure you specify which directory to operate on (i.e. DON'T JUST rm -rf /Volumes!) otherwise you will delete everything on every mounted disk, including your root drive (granted, it will throw permissions errors before doing anything to your OS first but still). Try to delete things in Finder if you’re not sure of your rm skills or if you don’t have a backup or time now to restore from that backup.

I think I messed up the Fusion Drive on the 1TB iMac (with BootCamp)

Theoretically everything is fine with your Fusion Drive. Fusion Drives look like this. Disk0 is your SSD with 121 GB and disk1 is your HDD with ~1 TB (~1.121 TB summed up).

The larger parts of your SSD (disk0s2) and your HDD (disk1s2) are pooled to a CoreStorage LVG (Fusion Drive: disk3) with a size of 967.8 GB. The rest is reserved for EFIs, a Recovery HD (alltogether ~1.3 GB) and your old Windows partition - now probably free space (~152 GB).

The logical volume 'Macintosh HD' (967.8 GB) spans disk0s2 and disk1s2. This is the first 'Macintosh HD' in picture 1. The volume 'Macintosh HD' - it's the one visible on the desktop - should ideally also have about 967.8 GB. This is the second 'Macintosh HD' in picture 1.
In fact it has only 852.67 GB (see picture 3).

In the second picture the logical volume 'Macintosh HD' is the first listed in black, the volume 'Macintosh HD' is the second listed in black, the other two 'Macintosh HD's listed in grey are the parts of your SSD and HDD dedicated to the logical volume 'Macintosh HD'.

In my opinion something went wrong after deleting various partitions with the Bootcamp Assistant/Disk Utility or in Windows.

Preparation:

Detach any external drive (especially your external Time Machine backup drive)
Restart to Internet Recovery Mode by pressing alt cmd R at startup.
The prerequisites are the latest firmware update installed, either ethernet or WLAN (WPA/WPA2) and a router with DHCP activated.
On a 50 Mbps-line it takes about 4 min (presenting a small animated globe) to boot into a recovery netboot image which usually is loaded from an apple/akamai server.

I recommend ethernet because it's more reliable. If you are restricted to WIFI and the boot process fails, just restart your Mac until you succeed booting.

Alternatively you may start from a bootable installer thumb drive (preferably Mavericks or Yosemite) or a thumb drive containing a full system (preferably Mavericks or Yosemite).

Now you may either repair CoreStorage or rebuild your Fusion Drive:

'Repair CoreStorage' (not recommended):

First i would try to check the volume 'Macintosh HD' with Disk Utility. If the volume is corrupted consider a reinstall of Mac OS X.
If the volume is ok quit Disk Utility
Open Terminal and enter diskutil unmountDisk /dev/LVIdentifier and both diskutil unmountDisk /dev/DiskContainingApple_CoreStorageIdentifier
In your case: first diskutil unmountDisk /dev/disk3 then diskutil unmountDisk /dev/disk0 and diskutil unmountDisk /dev/disk1
remove the EFI NO NAME partition with gpt remove -i IndexNumberOfEFINoName DiskIdentifier:
gpt remove -i 4 disk1
Remount the CoreStorage disks and then the Logical Volume:
In your case: first diskutil mountDisk /dev/disk0 and diskutil mountDisk /dev/disk1 and then diskutil mount /dev/disk3.

enter gpt -r -vvv show /dev/diskIdentfierOfApple_CoreStorage to get infos of your HDD CoreStorage disk.
In your case: gpt -r -vvv show /dev/disk1
It should look like this:

-bash-3.2# gpt -r -vvv show /dev/disk1
gpt show: /dev/disk1: mediasize=1000204886016; sectorsize=512;         blocks=1953525168
gpt show: /dev/disk1: PMBR at sector 0
gpt show: /dev/disk1: Pri GPT at sector 1
gpt show: /dev/disk1: GPT partition: type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, start=40, size=409600
gpt show: /dev/disk1: GPT partition: type=53746F72-6167-11AA-AA11-00306543ECAC, start=409640, size=1671210848
gpt show: /dev/disk1: GPT partition: type=426F6F74-0000-11AA-AA11-00306543ECAC, start=1671620488, size=1269760
gpt show: /dev/disk1: Sec GPT at sector 1953525167                               
     start          size  index contents                                        
         0             1        PMBR                                            
         1             1        Pri GPT header                                  
         2            32        Pri GPT table                                   
        34             6
        40        409600      1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
    409640    1671210848      2 GPT part - 53746F72-6167-11AA-AA11-00306543ECAC
1671620488       1269760      3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
1672890248     280634887
1953525135            32        Sec GPT table
1953525167             1        Sec GPT header

The free space on your HDD has 280634887 blocks. Please calculate the biggest block number dividable through 8. That's 280634880 blocks (á 512 bytes) which equals 143685058560 B or ~143.7 GB. Add the size of your HDD CoreStorage Physical Volume (852666400768 B) The result is 143685058560 B + 852666400768 B = 996351459328 B
Resize your HDD CoreStorage physical volume with diskutil cs resizeDisk HDDPVUUID newsize
In your case: diskutil cs resizeDisk 93892BE8-2B7F-4ABD-A4C3-984495DCD98D 996351459328b
Calculate the maximal size of your CoreStorage Logical Volume in diskutil cs list: (size disk0s2) + (size disk1s2) In your case that's 120988852224 B + 996351459328 B = 1117340311552 B. That should be the size of your refreshed Logical Volume Group.
Resize your Logical Volume with diskutil cs resizeVolume LVUUID LVGSize-128 MB In your case that's diskutil cs resizeVolume D237FFDC-7DA4-41D7-AC13-4CC7E5E8C0A0 1117212311552b. If you get an error (There is not enough free space...) choose a smaller size like 1117148311552b.
Quit Terminal and open Disk Utility.
Check your expanded CoreStorage Volume for errors.
Quit Disk Utility, choose your CS volume as startup disk and restart your Mac

'Rebuild Fusion Drive' (recommended if you have a Time Machine backup)

Booted to Internet Recovery Mode open Utilities → Terminal in the menubar and enter:
diskutil cs list to get the CoreStorage listing.
Copy the Logical Volume UUID, it's the fifth listed.
Now delete the Logical Volume with diskutil cs deleteVolume LVUUID.
In your case: diskutil cs deleteVolume D237FFDC-7DA4-41D7-AC13-4CC7E5E8C0A0.
Copy the Logical Volume Group UUID, it's the first listed in the listing of diskutil cs list.
Then delete the Logical Volume Group with diskutil cs delete LVGUUID.
In your case: diskutil cs delete 1EFE58BC-3613-44C4-86EE-D816F3B66E3E
Enter exit and quit 'Terminal'
Open 'Disk Utility'. Enter 'Ignore' if you are asked to fix the drives.
Choose your SSD and partition it: 1 Partition Mac OS X Extended (Journaled), hit the Options button and choose GUID Partiton table and hit OK and Apply.
Please check that the size is ~121 GB

Example:
Choose your HDD and partition it: 1 Partition Mac OS X Extended (Journaled), hit the Options button and choose GUID Partiton table and hit OK and Apply.
Please check that the size is ~1 TB

Example:
Quit Disk Utility and open Terminal
Enter diskutil list

Example (your disk identifiers and sizes are different of course: Your volume SSD probably has the Identifier disk0s2 and the size 121 GB and your volume HDD probably has the Identifier disk1s2 and the size 1.0 TB):
Enter diskutil cs create "Name" IdentifierSSD IdentifierHDD
In your case probably diskutil cs create "Macintosh HD" disk0s2 disk1s2.

Copy the resulting LVGUUID

Example:
Enter diskutil cs CreateVolume LVGUUID jhfs+ "Macintosh HD" 100%.

Example:
Enter diskutil cs list
Check the size of your Logical Volume. It should have the size ~1.121 TB

Example:
Quit Terminal
Open 'Disk Utility' and check your newly created volume for errors
Quit 'Disk Utility'
Attach your external Time Machine backup drive or check this answer if you use NAS or another network share.
Open 'Restore from Time Machine Backup'
Choose the appropriate Time Machine backup and restore your system
Reboot to your restored system.
Unmount and detach your Time Machine backup drive
Open 'Terminal' and enter 'diskutil list'
Check if your 'Recovery HD' is listed.
If your 'Recovery HD' is missing, usually reinstalling your current system with the latest available system installer (e.g. 'Install OS X Mavericks (10.9.5)' if Mavericks is currently installed) will recreate it without loosing any data. AFAIK Recovery Partition Creator 3.8 will NOT create a Recovery HD on CoreStorage volumes.
After reinstalling the system with the latest available system installer open App Store and install the latest security fixes.

Best Answer

Related Solutions

Have /Volumes/Storage Drive

I think I messed up the Fusion Drive on the 1TB iMac (with BootCamp)

Related Question