23 votes
Accepted

OS volume shows as type 'FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF'

A bootable OS X partition (except the Recovery HD) either has the GUID 48465300-0000-11AA-AA11-00306543ECAC for a standard OS X partition, the GUID 53746F72-6167-11AA-AA11-00306543ECAC for a ...
klanomath's user avatar
  • 65.9k
17 votes

How do I remove unused partition (El Capitan)?

You can't move the start block of a CoreStorage Volume Group ("BOOTCAMP" in your case) non-destructively (OK, there is a workaround: please check the Scattered Physical Volumes method at the end of my ...
klanomath's user avatar
  • 65.9k
8 votes

CoreStorage logic volume failed to mount

I ran into this. In my case it seems the problem was the mac wanted to run a filesystem check on it. After finding the fsck process and killing it, I could then mount the drive properly. $ ps -ef | ...
zeroimpl's user avatar
  • 181
7 votes
Accepted

APFS with external hard drives (non SSD)

APFS has no advantage over HFS+ (macOS extended) and vice versa in terms of post-mount performance when it comes to hard disks (non-SSD drives). However, macOS Sierra (10.12) or older can not access ...
Alper's user avatar
  • 3,691
6 votes

APFS with external hard drives (non SSD)

For HDD, if you are not going to install macOS, then use a Mac OS Extended (Journaled) or Mac OS Extended (Journaled, Encrypted) format. When using a hard drive just to store files, APFS or APFS (...
David Anderson's user avatar
5 votes
Accepted

DIY Fusion drive with 3 drives

It is possible to create a Logical Volume Group spanning over more than two disks. I doubt that it will differentiate between fast and slow HDD. The SSD part should work though. To accomplish this ...
klanomath's user avatar
  • 65.9k
4 votes
Accepted

Messed up 1TB Fusion Drive Partitions (on iMac 5K)

To expand your CoreStorage Logical Volume Macintosh HD you have to delete the blocking NO NAME EFI partition (disk1s5). The two unnamed parts (138.62 GB and 99.9 GB) are no partitions but unallocated ...
klanomath's user avatar
  • 65.9k
3 votes

How can I resize a partition on OSX 10.10.5

To get some additional un-allocated disk space on disk0 to create a new partition you have to shrink your CoreStorage Volume Group and all subsequent CoreStorage items. To resize the CoreStorage ...
klanomath's user avatar
  • 65.9k
3 votes
Accepted

Expanding a Fusion Drive partition

The good message: you can resize both partitions with on-board tools. The bad message: you can't change the start block of a partition to a lower block number (i.e expand Data to lower block numbers). ...
klanomath's user avatar
  • 65.9k
3 votes
Accepted

I erased the partition where Windows 10 was previously installed. How can I merge it with my OS X partition?

You can't simply merge a Bootcamp partition or empty space and a FileVault volume with Disk Utility (Boot Camp Assistant should handle this though). You first have to remove the Bootcamp partition and ...
klanomath's user avatar
  • 65.9k
3 votes

Crashed when creating a partition - now missing drive space!

In fact there isn't any space free on your disk in the sense of unallocated disk space. But you probably resized the Logical Volume Macintosh HD (disk1) residing in the Logical Volume Group Macintosh ...
klanomath's user avatar
  • 65.9k
3 votes
Accepted

Can't resize partition: "You can't perform this resize unless it has a booter"

Note: This answer assumes your drive is not hybrid partitioned. In other words, I assume your drive is using a GUID partitioning scheme and the Master Boot Record (MBR) table is fully protected. Also, ...
David Anderson's user avatar
3 votes

APFS with external hard drives (non SSD)

It would seem that one big advantage of using APFS, even on rotating drive, would be that it can take advantage of the copy-on-write technology, via the Finder or in Terminal with cp -c, thereby ...
Rick Gordon's user avatar
2 votes
Accepted

What's wrong with my Fusion Drive?

Probably your CoreStorage Logical Volume got corrupted! I recommend to backup your data to an external drive with Time Machine and rebuild the FusionDrive from scratch. Time Machine backup To ...
klanomath's user avatar
  • 65.9k
2 votes

Fusion drive unavailable after HD erase

You probably deleted your Logical Volume and the superior Logical Volume Family. To create a new one boot to Recovery Mode, open Terminal and simply enter: diskutil cs list #to get the lvgUUID (...
klanomath's user avatar
  • 65.9k
2 votes

Difference between enabling Time Machine's "Encrypt Backups" option, and encrypting from Disk Utility?

The command: diskutil list my_time_machine_disk_short_name will confirm you: # my_mac:/Users/bob % diskutil list disk5 /dev/disk5 #: TYPE NAME SIZE ...
dan's user avatar
  • 12k
2 votes

Missing Space on Drive using Core Storage after Boot Camp Assistant Failure

The use of Core Storage seems to be a common denominator in problems similar to mine. I used the sudo diskutil cs revert [Logical Volume guid] command in the Terminal application to get rid of Core ...
Alan Norton's user avatar
2 votes
Accepted

How to repair HFS+ partition?

The partition map is completely valid - the CoreStorage stack is messed up though. After creating a CoreStorage stack (e.g by enabling FileVault) the CoreStorage logical volume group should contain ...
klanomath's user avatar
  • 65.9k
2 votes

Expand OS X partition

The recommended method to expand Macintosh HD is to backup and remove your Windows partition with WinClone, expanding your OS X volume and restoring the Windows partition. This can also be done with ...
klanomath's user avatar
  • 65.9k
2 votes
Accepted

I want to triple-boot Lion, El Capitan, and WIndows. Howto?

iPartition used to be the go-to tool for this kind of task, but it cannot handle Core Storage volumes, which makes it a bit limited these days. Paragon have just brought out a new Hard Disk Manager ...
Tetsujin's user avatar
  • 112k
2 votes

Reverting a CoreStorage Volume

I ended up stumbling across the answer to my own questions (although David is right, I could have avoided it by following his steps). The guides I found all pointed to the first UUID, but it's ...
Coleman Kelly's user avatar
2 votes
Accepted

iMac disk partion FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF and fusion drive unlinked

The second (and the third) partition of your internal HDD got the wrong partition types, your data probably won't be lost. If one part of a Fusion Drive (i.e. disk0s2) suddenly get a wrong partition ...
klanomath's user avatar
  • 65.9k
2 votes
Accepted

Strange virtual disk. Delete or leave?

The internal virtual disk is a Logical Volume and part of a CoreStorage Logical Volume Group. CoreStorage itself is a logical volume manager similar to Linux' LVM. An LVM is an additional abstraction ...
klanomath's user avatar
  • 65.9k
2 votes

How can I *unlock* a CoreStorage logical-volume without mounting it?

Click the Unlock button in the top-right of DiskWarrior and enter the password to unlock the volume
Greg's user avatar
  • 21
2 votes

Remove Linux partition on Mac. CoreStorage problems

By accident the OP took one command in the answer Remove Ubuntu and grow Mac partition literally and entered: gpt add -b 409640 -i 2 -s 118430560 -t 53746F72-6167-11AA-AA11-00306543ECAC /dev/disk0 ...
klanomath's user avatar
  • 65.9k
2 votes
Accepted

Where are Core Storage instructions stored?

Starting up from a core storage volume -- whether encrypted or not -- requires a non-Core-Storage volume to hold the booter file. There's some coverage of this in reference section 26.1 of the Support ...
Gordon Davisson's user avatar
2 votes
Accepted

How do I print my logical volume group UUID to file?

Note: This answer is just example code as I only have one Core Storage Volume to test against, however, if there's more then one, the awk command could be modified to accommodate accordingly. Although ...
user3439894's user avatar
  • 57.4k
2 votes

CoreStorage logic volume failed to mount

Maybe check to see if you have any softwares running that block mounts, such as "disk arbitrator". In my case I forget to disable it, and after quitting it my disk mounted. (However, it may not show ...
Joy Jin's user avatar
  • 2,403
2 votes

Is it OK for Time Machine to take a long time to decrypt a freshly formatted encrypted disk?

I’ve had the same question, and after a bit of research (and based on my own experience) I’ve come to some conclusions: Encryption made by TimeMachine and Encryption made by disk utility is the SAME ...
KitsuneSama's user avatar
2 votes

Hard-Drive Storage size issues after partition Disk Utility

To run a whole-disk repair, you need to do it from the command-line: diskutil repairDisk /dev/disk1 Be sure to use the correct disk identifier (in this case it was /dev/disk1); in diskutil list you'...
lid's user avatar
  • 1,825

Only top scored, non community-wiki answers of a minimum length are eligible