Trouble with my partitions I have some trouble with my partitions on my Macbook Pro.
I created 2 partitions. One named "Yo" where I have installed Yosemite release. Another one named "Save" where I put all the stuffs I need to keep secure for work.

I want to create a 3rd one to re-install Mavericks just because one of my app is not working on Yosemite.

The trouble is that I can't do it through the Disk Utility GUI because everything is disabled. I saw a post here where they talked about using diskutil command in the terminal. I tried to follow it but I have something weird when I try to list all my disk. Here is the output:

$ diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *251.0 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage                         224.9 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
   4:                  Apple_HFS Save                    24.5 GB    disk0s4
   5:                 Apple_Boot Recovery HD             650.0 MB   disk0s5
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Yo                     *223.3 GB   disk1
                                 Logical Volume on disk0s2
                                 C5EE25C4-6BC6-4E56-961A-F43335118355
                                 Unencrypted


What I want to achieve is having these 3 partitions:


"Yo" -> 180GB
"Mavericks" -> 45GB
"Save" -> 25GB


Is that achievable without having to reinstall Yosemite and if so how can I succeed to do that?
The problem is that the Yo volume is inside a CoreStorage logical volume group. You can manipulate them from the command line, but the easiest thing to do is just revert it to a normal partition (in the terminal):

diskutil coreStorage revert /dev/disk1


This shouldn't cause data loss, but as always when working with partitions, back up anything you can't afford to lose. Once it's a normal partition, you should be able to manipulate it in Disk Utility again.

See man diskutil for more information.