Can't mount (Core Storage) encrypted volume anymore I use the following setup: 

SSD: System
Internal HDD: Data (Documents, Music, etc.)
Both disks are encrypted via the Core Storage utility.

It seems I can't mount the "Data" disk anymore.

I wanted to download a random pdf which failed. ("Downloads Folder" is on "Data" Volume)
Restarted the machine and now all aliased folders which refer to the "Data" volume have a question mark overlay rendered on their icon.

It's not possible to mount/unlock the "Data" disk through disk utility a.
The "Data" volume is, according to DiskUtility quite full (only 16MB left).
I have the suspicion that this small amount of space left in combination with the encryption causes some trouble.

What to do?

edit: output of diskutil cs list

+-- Logical Volume Group 5898542B-F53F-46A6-B529-C31152081292
=========================================================
Name:         Data
Status:       Online
Size:         499763888128 B (499.8 GB)
Free Space:   16777216 B (16.8 MB)
|
+-&lt; Physical Volume C6AAFA40-7F30-40C3-BC1E-A71A3C3DA757
|   ----------------------------------------------------
|   Index:    0
|   Disk:     disk2s2
|   Status:   Online
|   Size:     499763888128 B (499.8 GB)
|
+-&gt; Logical Volume Family 77CFA80C-6CEA-4FA5-8855-567C90FD2513
    ----------------------------------------------------------
    Encryption Status:       Unlocked
    Encryption Type:         AES-XTS
    Conversion Status:       Complete
    Conversion Direction:    -none-
    Has Encrypted Extents:   Yes
    Fully Secure:            Yes
    Passphrase Required:     Yes
    |
    +-&gt; Logical Volume E2DB4126-C04C-4AE1-B1AC-CDFF0218D537
        ---------------------------------------------------
        Disk:                  disk3
        Status:                Online
        Size (Total):          499428339712 B (499.4 GB)
        Conversion Progress:   -none-
        Revertible:            Yes (unlock and decryption required)
        LV Name:               Data
        Volume Name:           Data
        Content Hint:          Apple_HFS


Strange that the status says "Online" as well as that the encryption status is "Unlocked". If it's unmounted and not accessible it shouldn't be in unlocked state.
Not sure if this will be helpful, but I just wrote a script to unlock and mount a core storage Encrypted Disk like yours for myself. I had the same problem where I could get the disk unlocked, but not mounted. I finally realized that I needed a command to mount it after it was unlocked.

In terminal, you first have to unlock the Encrypted Disk and then you can mount it with a separate command. For you, that would look something like this:

diskutil cs unlockVolume E2DB4126-C04C-4AE1-B1AC-CDFF0218D537 -stdinpassphrase 


You will be prompted for the password to the Encrypted Disk. After this, your drive will be in an unlocked and unmounted state, so you still need to mount it with this command:

diskutil mount E2DB4126-C04C-4AE1-B1AC-CDFF0218D537


In case you were wondering, E2DB4126-C04C-4AE1-B1AC-CDFF0218D537 is the UUID of the disk you want to mount. I'm no scripting or CoreStorage pro, but your problem seemed similar to mine, so I hope this can help you. I got all this info from the diskutil man page if you run into any problems.