Previous 1 2 3 4 5 Next 119 Replies Latest reply: Sep 27, 2012 3:44 PM by Macnetmedia Go to original post
  • rharder Level 1 (10 points)

    @boli That's an interesting twist. You were able to convert 3TB drives connected with eSATA.


    It failed for me with FireWire 800, and I see from at least one other screenshot that someone had a failure with a USB connection.



    (back in Snow Leopard. Sigh)

  • boli Level 1 (75 points)

    I suspect it's the controller's fault, because it does weird stuff. From the  Anandtech Seagate 3TB review:

    Internally the 3TB drive uses 512-byte sectors, however the GoFlex dock emulates a 4K drive to allow for a single 3TB partition to be created in Windows.

    For me it works great however, because the OWC cases don't do weird stuff like that. And when connected internally it's not an issue either. I bet your disks would all work great if you'd put them inside your Macs...

  • rharder Level 1 (10 points)
    I bet your disks would all work great if you'd put them inside your Macs...


    Not a lot of room for that inside my flat panel iMac. LOL!





  • boli Level 1 (75 points)

    I know not everyone has a Mac Pro, I was just saying...


    So we (might) have this problem because of the 4k block emulation, which we have because of Windows. Great. I wonder if Apple can fix it.

  • rharder Level 1 (10 points)



    Deja vu. Didn't we go through this back in the System 7 days?




    This Knowledge Base article discusses the difference between logical blocks (512 bytes) and allocation blocks (varies based on drive size) back in the System 7. I guess the larger allocation block was a way of getting around the older HFS limitation of 65,536 logical blocks per volume.


    Interesting, but it still doesn't help me with my 3TB paper weight. OK, it's not a paperweight exactly, but encryption was the whole reason I wanted it...



  • DJKhan Level 1 (0 points)

    Sorry to hijack the thread, BUT i couldnt wait to ask, how did you put 3TB in your 27" imac? Is there a solution already out for the thermal heat sensor? please email me compuphile at

  • rharder Level 1 (10 points)

    No, no. I did not put a 3TB drive in my 27" iMac, and boli's just rubbing it in that he's got four 3TB drives in his Mac Pro.


    I have an external 3TB drive.



  • boli Level 1 (75 points)

    Same thing happened to a friend of mine, he made me aware of the issue which made me try for myself.


    Anyway, he's doing it "the old way" (for now): creating an encrypted disk image (or sparsebundle rather) on his external WD 3 TB drive.

  • McShifty Level 1 (0 points)

    Add my name to the list. Brand new 3 TB Seagate drive. Erased, didn't help. Repaired, didn't help either.

  • TychoS Level 1 (0 points)

    Same here, WD 3TB USB drive...


    It does sound very feasible that this is due to a workaround for Windows. Did anyone already ask Apple or a HDD vendor? I suppose if it's some kind of translation done in the drive it won't be fixable without a firmware update of the drive controller (USB to SATA bridge), or a workaround from Apple.

  • Jeremy Angoff Level 1 (0 points)

    Put me on the list: Brand new G-Drive Slim 500GB that wont convert to encrypted.

  • TychoS Level 1 (0 points)

    I think that's the first time someone's had this problem with a drive below 3TB. So it may not be caused by something involving a workaround with cluster sizes for Windows, a 500GB drive should work fine in Windows as it is... I hope Apple could fix this.

  • maiksd Level 1 (0 points)

    No, it's not the first time. I already reported somewhere above that I have that problem with a Samsung 640 GB external USB drive.


    I also reported that what distinguishes this drive from all my others is the sector size being not 512 bytes, in this case 1024 bytes. All your 3 TB drives will probably have 4096 bytes. So the bug is probably a hard dependency of the conventional 512 byte sector size.

  • boli Level 1 (75 points)

    Let's try to get an overview of the drives involved, and how they behave when used internally or externally.


    Drive overview:

    • G-Drive: some Hitachi HDDs use 4k sectors (for example the 7mm thin 500GB drive)
    • Seagate GoFlex 3TB: 512b sector size, but emulates 4k sectors when in external case
    • WD 3 TB: 4k sector size, emulates 512b sectors when used internally, but keeps 4k sector size in external case (MyBook)
    • Samsung 640 GB USB: uses 1k sector size


    Reported device block sizes:

    Part of the diskutil info /Volumes/YourDiskName output for various drives:

    • External WD 3TB drive (does not work):
      Device Block Size:        4096 Bytes
    • Internal WD 3TB drive (works):
      Device Block Size:        512 Bytes
    • External 6TB OWC RAID5 (works):
      Device Block Size:        512 Bytes
    • External 9TB OWC RAID5 (works):
      Device Block Size:        512 Bytes


    Can you guys try out the diskutil info /Volumes/YourDiskName command to see what Device Block Size is reported for your drives?


    In summary:

    So far what stepa assumed above seems to fit well: it looks as if core storage can't handle non-512b sectors.

    The fact that the WD 3TB drive works internally is probably due to the fact that it emulates 512b sectors, whereas it presents 4k sectors in an external case. It would be interesting to see what would happen when one of the other drives would be used internally (especially if they don't present 512b sectors)

  • maiksd Level 1 (0 points)

    Samsung S2 Portable, external USB 640 GB drive, product ID 0x1f06, vendor ID 0x04e8:

    Total Size:               639.8 GB (639791054848 Bytes) (exactly 1249591904 512-Byte-Blocks)

    Device Block Size:        1024 Bytes


    Samsung S2 Portable, external USB 640 GB drive, product ID 0x1f06, vendor ID 0x04e8 (same as above!):

    Total Size:               639.5 GB (639472283648 Bytes) (exactly 1248969304 512-Byte-Blocks)

    Device Block Size:        512 Bytes


    Two versions of the same product, even with the same USB product ID, but different sector sizes.


    I have several other disks, all with 512 Bytes, which all work fine with Lion encryption.

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