Home > Mac, mods, Tech Tips, Technology > 128Gb+ Large HDD (LBA48) support on the G4 Cube with Leopard, for free.

128Gb+ Large HDD (LBA48) support on the G4 Cube with Leopard, for free.

It’s possible to access the entire space of any large hard disk without drivers, that means without the need for the $25 Speed Tools ATA Hi-Capacity Support Driver. This also means that Leopard will work, too.

With the magic of the Open Firmware, as with the Open Firmware fake CPU speed hack, it’s possible to hack the Open Firmware to enable large disk support, otherwise known as LBA48.

I have only tested this with Leopard and Tiger, so I can’t vouch for earlier OS-X builds. however, note that this DOES NOT WORK FOR OS9. For OS9, you will still need the speedtools driver available here:

This time, however, we need to write this to the non-volatile RAM so that the changes aren’t lost on reboot.

  • Reboot or Power up your Cube
  • Hold down Command + Option + O + F simultaneously as soon as the reboot starts.

You should now be at the Open Firmware prompt. Note that this is NOT the BASH prompt, so don’t try anything here.

  • Type in the following, exactly. Please note that the Underscore “_” is used to indicate a space.
  • Press Ctrl+C to exit from nvedit.

That’s it. Now boot up and go to “About My Mac” to confirm the disk size.

If your disk was already formatted, it will have its original 128Gb partition and a region of inaccessible space at the end. It’s probably easiest to reformat the disk with a new partition scheme, unless you have some terminal disk utility or related tricks up your sleeve.

  • This hack will last until you reset the NV RAM (P RAM).
  • Similarly, if you hose your open firmware settings, use this fact to your advantage, perform a PRAM reset and start again.

If you do repartition the disk, it’s probably wise not to cross the 128Gb boundary with a partition, in case you ever have to reset the NV RAM, in which case you’ll only be able to access the first 128Gb of the the hard-disk. By splitting the disk at 128Gb, you’ll ensure that only whole partitions are visible and any partition after the 128Gb will be entirely invisible.

In my case, I made a front partition of 128Gb, and the remaining 30 something Gigs into an extra partition for temprorary files.

Thanks to the Cube Kaizou (Cube Mods) page on Studio Milehigh (!!!) homepage. Apparently his own Cube died at the end of April last year but he has left his legacy of Cube update experience online.

Categories: Mac, mods, Tech Tips, Technology Tags: , , ,
  1. Aaron
    September 17, 2008 at 4:06 am

    Question about the 128-GB boundary:
    Does that mean a 128-GB volume, or a volume that ends at exactly 128 GB from the start of the disk? In the latter case, one would have to subtract the space allocated to the partition map, and any free space preceding the first volume, from the 128 GB in setting the size of the volume.

  2. nanchatte
    September 17, 2008 at 4:19 am


    What you said above would be the ideal situation, yes. However:

    It’s not possible to set the size exactly to 128Gb using the graphical tool supplied without additional, quite complex calculations. And in most cases, such accuracy is unnecessary.

    The idea is to minimise the possibility of having data that crosses the 128Gb boundary. That is because any data after the 128gb boundary will not be accessible to the booting computer until the OS is running.

    So long as you don’t need to access any of the data that was created beyond the 128Gb limit, your computer can boot safely and Safe Mode will not cause any problems.

    The key is to make sure that the second partition starts somewhere after the 128Gb boundary to make it completely invisible to the boot process and Safe mode otherwise the second partition will be visible at boot time but only a little of its contents will actually by accessible, so when the OS tries to access it, read errors will occur.


  3. August 11, 2009 at 9:08 am

    Thanks for the invaluable information. I just successfully installed two extra 300GB drives in my Quicksilver 733mhz. However, the last drive (mounted on the bus with the optical drive) only shows up as a 128GB in System Profiler and Disk Utility, yet when I look at the main (and only) partition it has the correct capacity and available space. I’m just a little worried about this. Should I be? Or is there a different hack for drives on this bus?

    • nanchatte
      August 18, 2009 at 6:00 pm

      Scott, in any situation, with an unsupported BIOS, you should never have a partition that crosses the 128GiB line (Thats 128 Gigs when measured in binary = about 137.4 GB as measured in decimal)
      in case you ever need to restore with Target disk mode or software such as Diskwarrior which will cause irreversible data loss to that partition.

      Instead, you should partition your drive as close to that threshold as possible in order to prevent data loss.
      This will make sure that all data on the partition before the threshold is available.

      You can use disk manager of Leopard to shrink the partition down to the 128GB threshold and then create a new partition.
      Remember regardless of what the OS lets you see, low level stuff like Target disk will only be able to read and write to the first 128GB on older machines even if they report more space available.

      Thus, all or nothing is a better approach (i.e. all of a partition before the threshold and all of a second after.

      If you are paranoid, you could even make the first partition a couple of gigs smaller, add a 4 or 5 gig buffer partition and then add the final, large partition. Then erase or just unmount the middle partition, leaving it RAW or unformatted.


      • November 8, 2009 at 8:17 am

        Thanks so much for the advice. Does this also apply when using a Sonnet card to install large SATA drives?

  4. August 29, 2010 at 5:53 am

    No, using a card bypasses the built-in bus limit. Then you’re typically only limited by the capability of the card – SATA or ATA.

  1. April 30, 2008 at 11:19 am
  2. September 2, 2014 at 6:32 am

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