Depending on your requirements there is a second method to quickly resize and add a second volume: resize the CoreStorage Volume (instead of the whole group) and add a second CoreStorage Volume inside the existing CoreStorage Volume Group:
Preparation:
- Backup your data.
- Detach any external drive (especially your external Time Machine backup drive) except your external boot drive.
- Boot from your external drive or a bootable installer thumb drive (Mavericks or Yosemite)/a thumb drive containing a full system (Mavericks or Yosemite).
or
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 to 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.
Modify CoreStorage stack:
Open Disk Utility and check your disks for errors. Repair them and quit Disk Utility.
Open /Applications/Utilities/Terminal First you should get an overview of your disks and the partition layout:
Enter
diskutil list:
Example listing:
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *500.1 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_HFS Fenchurch 80.0 GB disk0s2
3: Apple_HFS BxxxxxData 70.0 GB disk0s3
4: Apple_CoreStorage 349.0 GB disk0s4
5: Apple_Boot Recovery HD 650.0 MB disk0s5
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *100.1 GB disk1
1: EFI EFI 209.7 MB disk1s1
2: Apple_HFS BlinkenDonx 99.9 GB disk1s2
/dev/disk2
#: TYPE NAME SIZE IDENTIFIER
0: Apple_HFS YoodenVranx *348.6 GB disk2
Logical Volume on disk0s4
with disk0: your internal disk, disk1: a fictional external boot drive with 100 GB containing your boot volume (BlinkenDonx) and disk2: your CoreStorage Volume Group YoodenVranx residing in disk0s4.
- Enter
diskutil cs list
Example listing:
CoreStorage logical volume groups (1 found)
|
+-- Logical Volume Group A629E051-D7B0-4B8C-A803-074F62704636
=========================================================
Name: YoodenVranx
Status: Online
Size: 349046696192 B (349.0 GB)
Free Space: 16777216 B (16.8 MB)
|
+-< Physical Volume 90C09FC0-4215-4871-901B-70E2C9C7D464
| ----------------------------------------------------
| Index: 0
| Disk: disk0s2
| Status: Online
| Size: 349046696192 B (349.0 GB)
|
+-> Logical Volume Family F6962E38-50E4-4458-BFE6-CF2E179352F5
----------------------------------------------------------
Encryption Status: Unlocked
Encryption Type: None
Conversion Status: NoConversion
Conversion Direction: -none-
Has Encrypted Extents: No
Fully Secure: No
Passphrase Required: No
|
+-> Logical Volume BD36C73D-860D-4DC6-B125-AD624F448B88
---------------------------------------------------
Disk: disk2
Status: Online
Size (Total): 348696696192 B (348.6 GB)
Conversion Progress: -none-
Revertible: Yes (no decryption required)
LV Name: YoodenVranx
Volume Name: YoodenVranx
Content Hint: Apple_HFS
Now shrink the existing CoreStorage Volume with:
diskutil cs resizeVolume LVUUID size
with LVUUID: UUID of the existing Logical Volume. Example:
diskutil cs resizeVolume BD36C73D-860D-4DC6-B125-AD624F448B88 279500m
Add a new Logical Volume in the existing CoreStorage Volume Group with:
diskutil cs createVolume LVGUUID type name size
with LVGUUID: UUID of the existing Logical Volume Group, type: file system, size: percentage or size.
Examples:
diskutil cs createVolume A629E051-D7B0-4B8C-A803-074F62704636 jhfs+ ElCapitan 100%
All the available free space in the CoreStorage Volume Group will be allocated to the new Logical Volume.
diskutil cs createVolume A629E051-D7B0-4B8C-A803-074F62704636 jhfs+ ElCapitan 50000m
50,000 MB (50 GB) of the available free space in the CoreStorage Volume Group will be allocated to the new Logical Volume.
- Enter exit and quit Terminal.
- Open Disk Utility and check your shrunk and the new CoreStorage volume for errors.
- Quit Disk Utility.
- Reboot to your main volume.