Where is all the data?

Discussion in 'OS X Yosemite (10.10)' started by Blacksmith76, Sep 14, 2015.

  1. Blacksmith76 macrumors newbie

    Sep 14, 2015

    I hope someone can help. I was using Disc Utility today and saw that the top HD is completely full and the one underneath has loads of room. It is causing my Mac to be troublesome yet I can't find where all this data is. I have searched my Library folder which has 6GB in it. Here is a screenshot of the Disc Utility page showing both HD drives.

    Any suggestions on where I find this mass of data so I can deal with it?

    Thanks in advance! Screen Shot 2015-09-14 at 09.36.25.png Screen Shot 2015-09-14 at 09.36.30.png
  2. Toutou macrumors 6502a


    Jan 6, 2015
    Prague, Czech Republic
    The "top" HD is basically full of the "bottom" HD. The bottom HD is what your system works with, his Mac partition. The top HD is the physical device inside the MacBook. So it's completely OK. There is one logical partition almost exactly the size of the actual storage. If there's anything wrong with your MacBook, it's not caused by this. Maybe tell us what's happening?
  3. Blacksmith76 thread starter macrumors newbie

    Sep 14, 2015
    Thanks Toutou, My Macbook Applications have been crashing recently and I had a message pop up telling me that my memory was almost full. So if the "top" HD is the physical devise and is almost full, how can this be healthy for it? Also as the "bottom" HD increases in size how will the "top" one cope with it if it is full?

    My wife has a Mac and this one shows virtually and equal amount on each.
    Forgive my ignorance but you state "top" and "bottom" in ""..". What is the correct term for each:).

    Thanks for your help.
  4. NoBoMac, Sep 18, 2015
    Last edited: Sep 18, 2015

    NoBoMac macrumors 68000

    Jul 1, 2014
    You have full disk encryption turned on, and your Disk Utility does not have Debug > "Show All Partitions" checked, so, it's a little confusing, not the whole picture.

    With the "Show All Partitions" turned on, you will see something like this:

    Screen Shot 2015-09-18 at 8.46.12 AM.png

    As Toutou said, the first line is the physical drive. Everything under it are the partitions that are on the drive. EFI is the "BIOS"-like boot functions for the machine, "Recovery HD" is for system recovery. Note, there are two "Macintosh HD" items. When the disk gets encrypted, you get a partition type listed as "Core Storage Physical Volume" that is about the full size of the disk. That's the encrypted partition/drive. When you start the computer, that encrypted glob of data gets decrypted and turned into the second "Macintosh HD" you see. Think of that second volume as a "virtual drive". That drive/volume/partition expands and contracts within the size of the encrypted disk and gets re-written to the core storage (encrypted) volume.

    So, there is room to write data to "disk", it's just that you are dealing with partitions and having a level of indirection going on to deal with the encryption. Basically, the physical drive is full of encrypted storage, hence, why the drive shows a "full", when the computer's partition really isn't full.

    ADD: to get a better idea of how this all lays out, and imo, a better representation than Disk Utility, bring up a Terminal window and issue the following command: diskutil cs list

    OH AND: is it possible the memory message is referencing RAM vs disk? Depending on apps running, some are not very good at freeing up memory. Some, especially if running a while, are plain old resource hogs (browsers, especially with lots of tabs open). Fire off "Activity Monitor" in the Utilities folder (under Applications) and click the Memory tab to see if your RAM is busting at the seams.

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