Q: HELP! I have 7 partitions, 2 EFI, 2 MacHD, etc.

That looks normal, I have…

bless --info /

finderinfo[0]: 1173996 => Blessed System Folder is /System/Library/CoreServices

finderinfo[1]: 1631471 => Blessed System File is /System/Library/CoreServices/boot.efi

finderinfo[2]:      0 => Open-folder linked list empty

finderinfo[3]:      0 => No alternate OS blessed file/folder

finderinfo[4]:      0 => Unused field unset

finderinfo[5]: 1173996 => OS X blessed folder is /System/Library/CoreServices

64-bit VSDB volume id:  0xE73BFFD1189AA2E5

'bless --info' doesn't alter the setup. It tells us that partition is setup to boot using the listed folder & boot.efi.

See if this alters it…

sudo bless --folder /System/Library/CoreServices --file /System/Library/CoreServices/boot.efi --setBoot --verbose

Since you seem to be using a different boot disk you can also try selecting the startup disk from the other OS to see if that can resolve it. Other posts have said that bless helped, whilst others said that Startup disk from another disk resolved the same 'Building boot caches…' issue. They are essentially the same thing IIRC.

This is what I get.

sudo bless --info /

Password:

finderinfo[0]:     45 => Blessed System Folder is /System/Library/CoreServices

finderinfo[1]: 9795899 => Blessed System File is /System/Library/CoreServices/boot.efi

finderinfo[2]:      0 => Open-folder linked list empty

finderinfo[3]:      0 => No alternate OS blessed file/folder

finderinfo[4]:      0 => Unused field unset

finderinfo[5]:     45 => OS X blessed folder is /System/Library/CoreServices

64-bit VSDB volume id:  0x3EE7659409EF64D1

An external clean boot from a clean OSX install should help clean up boot caches.

On a 2012 Mac mini (Mavericks 10.9.5) with 256GB SSD+1TB HDD and DIY Fusion drive, this is what it looks like.

$ diskutil list

/dev/disk0

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                        *256.1 GB   disk0

   1:                        EFI EFI                     209.7 MB   disk0s1

   2:          Apple_CoreStorage                         128.0 GB   disk0s2

   3:                 Apple_Boot Boot OS X               134.2 MB   disk0s3

   4:       Microsoft Basic Data BOOTCAMP                127.7 GB   disk0s4

/dev/disk1

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                        *500.1 GB   disk1

   1:                        EFI EFI                     209.7 MB   disk1s1

   2:                  Apple_HFS OSX-Server-ic2sHD       499.8 GB   disk1s2

/dev/disk2

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                        *1.0 TB     disk2

   1:                        EFI EFI                     209.7 MB   disk2s1

   2:          Apple_CoreStorage                         999.3 GB   disk2s2

   3:                 Apple_Boot Boot OS X               650.0 MB   disk2s3

/dev/disk3

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:                  Apple_HFS OSX-FusionHD           *1.1 TB     disk3

/dev/disk5

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:     Apple_partition_scheme                        *300.1 GB   disk5

   1:        Apple_partition_map                         32.3 KB    disk5s1

   2:                  Apple_HFS Backups                 137.0 GB   disk5s3

   3:                  Apple_HFS Music                   137.2 GB   disk5s5

   4:                  Apple_HFS Extra Space             25.5 GB    disk5s7

/dev/disk6

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                        *2.0 TB     disk6

   1:                        EFI EFI                     209.7 MB   disk6s1

   2:                  Apple_HFS Time Machine Backups    2.0 TB     disk6s2

/dev/disk7

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:     Apple_partition_scheme                        *16.0 MB    disk7

   1:        Apple_partition_map                         32.3 KB    disk7s1

   2:                  Apple_HFS Flash Player            16.0 MB    disk7s2

$ diskutil cs list

CoreStorage logical volume groups (1 found)

|

+-- Logical Volume Group DF140929-90E7-48E1-AC3D-C9C75BA88D1D

    =========================================================

    Name:         OSX-FusionHD

    Status:       Online

    Size:         1127375384576 B (1.1 TB)

    Free Space:   69632 B (69.6 KB)

    |

    +-< Physical Volume C856A74C-EB57-4D1F-8223-0A22215218ED

    |   ----------------------------------------------------

    |   Index:    0

    |   Disk:     disk0s2

    |   Status:   Online

    |   Size:     128030257152 B (128.0 GB)

    |

    +-< Physical Volume 80D91A14-CCC9-47B1-B071-B9ADFF23924F

    |   ----------------------------------------------------

    |   Index:    1

    |   Disk:     disk2s2

    |   Status:   Online

    |   Size:     999345127424 B (999.3 GB)

    |

    +-> Logical Volume Family 019D610F-21AC-4B54-AB0A-6D5F90D520A7

        ----------------------------------------------------------

        Encryption Status:       Unlocked

        Encryption Type:         None

        Conversion Status:       NoConversion

        Conversion Direction:    -none-

        Has Encrypted Extents:   No

        Fully Secure:            No

        Passphrase Required:     No

        |

        +-> Logical Volume D9DC0F70-38C7-4AE6-BAC4-CFBE0F8D4F68

            ---------------------------------------------------

            Disk:                  disk3

            Status:                Online

            Size (Total):          1118844862464 B (1.1 TB)

            Conversion Progress:   -none-

            Revertible:            No

            LV Name:               OSX-FusionHD

            Volume Name:           OSX-FusionHD

            Content Hint:          Apple_HFS

and Disk Utility shows (without Debug Menu)

With Debug Menu (List All Partitions) and EFI partitions from both disks mounted. Get Info from each mounted EFI shows the difference between the two.

The EFI partitions can be manually mounted/unmounted and do not stay on the Desktop.

1. Can you right-click on each EFI and click on Get Info?

2. The CS volumes spans two physical disks, hence it shows up with that name, twice, in the DU list pane.

3. The mount of EFI does not persist across reboots.

4. Do you have a pending Firmware Update for your Mac?

5. Desktop can have icons whose underlying objects have been deleted/unmounted. These can be addressed and cleaned up.

Maybe we should see what is inside autodiskmount.plist …

sudo defaults read /Library/Preferences/SystemConfiguration/autodiskmount.plist

It looks like it could be from an old hint for mounting disks before login, I wonder if there is an interaction on 10.10 with that?  I'd have expected more reports about it by now?

Loner T do want to test - I don't have a multi disk CS setup on 10.10. I believe the original hack was…

sudo defaults write /Library/Preferences/SystemConfiguration/autodiskmount AutomountDisksWithoutUserLogin true

Remove it via…

sudo defaults delete /Library/Preferences/SystemConfiguration/autodiskmount AutomountDisksWithoutUserLogin

I believe you can destroy the CS group in Terminal via recovery, so hold on for Loner T, (s)he can probably step through that.

If you want to destroy the entire CS volume, here are the commands in sequence. This should be executed when booted in Internet Recovery (if supported on your Mac). If you cannot get to Internet Recovery, ML 10.8.2-10.8.5 is the oldest version with CS commands, which can be a bit buggy and untrustworthy. Mavericks and/or Yosemite external boot is a better path, if necessary. This will destroy all your data on the internal drive. Please backup what you want to save, before the following steps are executed. Do not use Disk Utility during this procedure, it will try to 'Fix' and undo all your work.

1. Delete the Macintosh HD Logical Volume - diskutil cs deleteVolume 77D2C79F-AFAB-4E79-B0A4-E1E7F07F5D8F

2. Delete the Macintosh HD Logical Volume Group - diskutil cs delete 4595DA22-0057-4CBE-A0A2-2E64596FAF8F

3. Initialize the SSD part of the Fusion drive  - diskutil eraseDisk JHFS+ SSD disk0

4. Initialize the HDD part of the Fusion drive  - diskutil eraseDisk JHFS+ HDD disk1

5. Rebuild the Fusion Drive. Please note that the SSD MUST come first, otherwise the performance of the Fusion drive will be reduced significantly. Machine reboots can cause the diskN to be renumbered. A verification using diskutil list is highly recommended to ensure that the correct disk and order is picked for the following command. (Note: I have chosen a name which avoids confusion between a LVG and an LV, but personalize it as you see fit).

     diskutil cs create OSX-MacintoshLVG disk0s2 disk1s2

7. This LVG can now be split/resized into smaller LVs of the size permitted by total available space. The following three verbs of CS vocabulary can be used. The syntax is included for clarity.

$ diskutil cs createVolume

Usage:  diskutil coreStorage createVolume lvgUUID|lvgName type name size

        [-stdinpassphrase | -passphrase [passphrase]]

Add a new logical volume to a CoreStorage logical volume group.

 

Type is the file system to initialize on the new logical volume. Valid types

are Journaled HFS+ or Case-sensitive Journaled HFS+ or their aliases.

 

Size is the amount of space to allocate from the parent logical volume group.

Valid sizes are floating-point numbers with a suffix of B(ytes), S(512-byte-

blocks), K(ilobytes), M(egabytes), G(igabytes), T(erabytes), P(etabytes),

or (%) a percentage of the current size of the logical volume group.

 

Example: diskutil coreStorage createVolume

         11111111-2222-3333-4444-555555555555 jhfs+ myLV 10g

 

$ diskutil cs resizeVolume

Usage:  diskutil coreStorage resizeVolume

        lvUUID|MountPoint|DiskIdentifier|DeviceNode size

Resize a logical volume, which is one of one or more disks that consume storage

out of a logical volume group. The logical volume group will have more or less

available space after this operation, if it was a shrink or grow, respectively.

Example: diskutil coreStorage resizeVolume

         11111111-2222-3333-4444-555555555555 10g

 

$ diskutil cs deleteVolume

Usage:  diskutil coreStorage deleteVolume

        lvUUID|MountPoint|DiskIdentifier|DeviceNode

Delete a logical volume. The volume must be unlocked.

Example: diskutil coreStorage deleteVolume 11111111-2222-3333-4444-555555555555

Some of these are hidden or not documented on man pages, but Usage can be found, if verbs are known (I have asked these to be documented and supported for quite some time, to no avail).

It is a mystery and a challenge to solve. If they disappear in a few seconds, can you check Applications -> Utilities -> Console logs for anything related to EFI?

Here is my test and the corresponding messages in Console.

mkdir /Volumes/EFI

$ sudo mount -t msdos /dev/disk0s1 /Volumes/EFI

Password:

$ ls -l /Volumes/EFI

total 67

-rwxrwxrwx  1 MyName  staff  33598 Oct 16 16:12 BOOTLOG

drwxrwxrwx  1 MyName  staff    512 Aug 19 15:30 EFI

 

$ diskutil umount /Volumes/EFI/

Volume EFI on disk0s1 unmounted

2/7/15 9:57:26.990 AM sudo[1115]: xxxxxx : TTY=ttys000 ; PWD=/Users/MyName ; USER=root ; COMMAND=/sbin/mount -t msdos /dev/disk0s1 /Volumes/EFI

2/7/15 9:58:19.344 AM authd[87]: Succeeded authorizing right 'system.volume.internal.unmount' by client '/usr/sbin/diskutil' [1126] for authorization created by '/usr/sbin/diskutil' [1126] (13,0)

2/7/15 9:58:19.346 AM authd[87]: Succeeded authorizing right 'system.volume.internal.unmount' by client '/usr/libexec/diskarbitrationd' [41] for authorization created by '/usr/sbin/diskutil' [1126] (2,0)

AutomountDisksWithoutUserLogin = 0; means that option is disabled. You could probably delete the plist since it doesn't seem to be a default option.

It's very odd that they mount & disappear.

After step 5, you have a 1.1 TB Fusion Drive and a default LV. You should be able to see it using diskutil cs list.

The reason for including resizeVolume/deleteVolume/createVolume verbs is to let you know that they can be used if you need to split/resize the default LV. The default LV is sufficient for being partitioned by BCA, so you do not need any additional work.

All UUIDs come from your machine, steps 1 and 2 are also from the output of you diskutil cs list. They will change after step 5 and new UUIDs will generated.

… Building boot caches on boot helper partition failed …

Cross reference: http://forums.macrumors.com/showthread.php?p=20687163#post20687163 under Very weird problem: Too many hidden partitions, can't repartition! – MacRumors Forums

I did into spend much time on the ML 10.8 thread (170+ pages), but the outstanding questions in this discussion are

1. Bootcache build failure. (Bless output looks reasonable).

2. The momentary mounting of EFI. (Console logs would really help).

The vagaries of DU and its interaction with CS volumes will get addressed by Apple at some point. I have been after them for many moons.