Create new partition on encrypted volume in OS X Lion

disk-utility encryption osx-lion

Updated: see below.

I encrypted a 500 GB partition on an external 1TB drive on OS X Lion. The other 500 GB was not used yet and I want to create another partition on the external drive now. Disk utility will not let me do this and refers to the command line utility diskutil, noting that the drive contains CoreStorage physical volumes.

I have looked around in the utility diskutil but so far I haven't found anything useful:

  • diskutil cs createVolume does not work because I first have to resize the Logical Volume Group, apparently.
  • diskutil resizeVolume might work, but this does not work on CoreStorage volumes, so I'm afraid I might break things (i.e. my encrypted volume occupies disk2s1, disk2s2 and disk2s3 at the same time) (see my diskutil output)

Some background info is given in an Ars Technica review, but this provides little information on how to proceed. This Macworld article instructs how to resize a volume, but I don't think this is applicable to CoreStorage volumes.

My diskutil list output:

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.1 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:          Apple_CoreStorage                         499.2 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS OSX                    *498.9 GB   disk1
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk2
   1:                        EFI                         209.7 MB   disk2s1
   2:          Apple_CoreStorage                         499.8 GB   disk2s2
   3:                 Apple_Boot Boot OS X               134.2 MB   disk2s3
/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS TimeMachine disk       *499.5 GB   disk3

my diskutil cs list output here:

CoreStorage logical volume groups (2 found)
|
+-- Logical Volume Group UUID1
|   =========================================================
|   Name:         OSX
|   Sequence:     1
|   Free Space:   0 B (0 B)
|   |
|   +-< Physical Volume UUID1.1
|   |   ----------------------------------------------------
|   |   Index:    0
|   |   Disk:     disk0s2
|   |   Status:   Online
|   |   Size:     499248103424 B (499.2 GB)
|   |
|   +-> Logical Volume Family UUID1.2
|       ----------------------------------------------------------
|       Sequence:               8
|       Encryption Status:      Unlocked
|       Encryption Type:        AES-XTS
|       Encryption Context:     Present
|       Conversion Status:      Complete
|       Has Encrypted Extents:  Yes
|       Conversion Direction:   -none-
|       |
|       +-> Logical Volume UUID1.2.1
|           ---------------------------------------------------
|           Disk:               disk1
|           Status:             Online
|           Sequence:           4
|           Size (Total):       498929332224 B (498.9 GB)
|           Size (Converted):   -none-
|           Revertible:         Yes (unlock and decryption required)
|           LV Name:            OSX
|           Volume Name:        OSX
|           Content Hint:       Apple_HFS
|
+-- Logical Volume Group UUID2
    =========================================================
    Name:         TimeMachine disk
    Sequence:     1
    Free Space:   0 B (0 B)
    |
    +-< Physical Volume UUID2.1
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk2s2
    |   Status:   Online
    |   Size:     499796238336 B (499.8 GB)
    |
    +-> Logical Volume Family UUID2.2
        ----------------------------------------------------------
        Sequence:               9
        Encryption Status:      Unlocked
        Encryption Type:        AES-XTS
        Encryption Context:     Present
        Conversion Status:      Complete
        Has Encrypted Extents:  Yes
        Conversion Direction:   -none-
        |
        +-> Logical Volume UUID2.2.1
            ---------------------------------------------------
            Disk:               disk3
            Status:             Online
            Sequence:           4
            Size (Total):       499477467136 B (499.5 GB)
            Size (Converted):   -none-
            Revertible:         Yes (unlock and decryption required)
            LV Name:            TimeMachine disk
            Volume Name:        TimeMachine disk
            Content Hint:       Apple_HFS

Update:

After looking around for more information it seems that currently CoreStorage volumes are not so flexible. There is a useful blogpost listing some undocumented features, but still resizing a CoreStorage volume does not seem to work.

Using the old diskutil commands do not solve the problem:

  • diskutil resizeVolume disk2s2 R is not possible because it is a CoreStorage partition/volume
  • diskutil resizeVolume disk3 R is the same
  • diskutil partitionDisk does not work because it deletes all volumes first

Using CoreStorage routines also runs into trouble

  • diskutil cs resizeDisk does not work because the CoreStorage physical volume is bound to the limits of the regular partition disk2s2
  • diskutil cs addDisk is not possible because I cannot repartition disk2 without destroying it
  • diskutil cs resizeVolume does not work because the logical volume group is not big enough

In the end I am now reverting the encryption and will re-partition the drive non-destructively with Disk Utility after that is complete.


There are multiple aspects to this, I'll try to encompass all answers (to the best of my knowledge) in one post.

Resizing a volume in coreStorage world

… resize a volume, but I don't think this is applicable to CoreStorage volumes. …

True, not applicable. In folder http://www.wuala.com/grahamperrin/public/2011/07/30/b/ at the tail of file 2011-07-30 07.14.txt for a logical volume with partition type Apple_HFS there's the following string:

Volume format does not support resizing

diskutil coreStorage revert …

If you wish to resize what is currently an Apple_CoreStorage partition, you must:

  1. begin converting backward

  2. allow conversion to complete.

Following completion of backward conversion

Generally

If the volume to be reverted is a startup volume, then completion should be followed by a restart of the operating system.

For your disk2

A restart may be unnecessary, but should do no harm. Considering the use of part of disk2 by Time Machine, my hunch is that a post-conversion restart would be timely.

Adding a volume within coreStorage world to free space on disk2

If you wish this, bear in mind that with or without encryption, the volume may be unrecognisable by any operating system that lacks support for Apple Core Storage.

diskutil coreStorage createVolume …

My attempts in this area failed, typically with the following response:

Error: -69720: There is not enough free space in the Core Storage Logical Volume Group for this operation

(I do have related questions but they're off-topic from the opening question.)

Increasing the proportion of a physical volume that is given to a logical volume family

AFAICT not possible. This concept may be purely my imagination (I don't pretend to understand all things Core Storage-related).

Adding a volume without/alongside coreStorage world to free space on disk2

Using Apple software included with Mac OS X 10.7 (Build 11A511)

If you wish the free ~half of your disk2 to be a volume that will be compatible with (say) Snow Leopard, alongside the encrypted ~half, then you can/should:

  1. completely revert the ~half that currently uses Core Storage, probably

    diskutil coreStorage revert /Volumes/TimeMachine\ disk

  2. use Disk Utility to add a partition with a compatible file system

  3. use the Time Machine pane of System Preferences (or if confident, diskutil) to put your TimeMachine disk in coreStorage world, with encryption.

After using Disk Utility to manage partitions, repair all volumes

Hint: in some environments, a use of Disk Utility 12 (346) may result in a need to repair, a need that is not immediately obvious. After using this version of Disk Utility to add or resize a partition, consider verifying all physical and logical volumes associated with that physical disk.

Using third party utilities

At least one third party utility can add a partition with a JHFS+ file system without/alongside coreStorage world.

Not all such utilities are logical partition/volume aware, so be prepared to unmount logical volumes before attempting writes to disk.

More generally: with any third party disk utility, proceed with caution in and around coreStorage world. Claims of "complete" compatibility with Lion may be contentious.

HTH Graham

More items, for reference only, in the following folders:

  • http://www.wuala.com/grahamperrin/public/2011/07/30/b/
  • http://www.wuala.com/grahamperrin/public/2011/07/31/a/

I look forward to Apple publishing more useful information on these subjects.

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