Significance of OSX installation and 1st 8 GB of HD?

Posted:
in macOS edited January 2014
Is there some requirement like this? How does this come about?

Comments

  • Reply 1 of 14
    jambojambo Posts: 3,036member
    It only counts for beige G3 (and possibly Bondi iMac). If you have a drive larger than 8GB which is partitioned, you can only install OS X on a partition that is completely within the first 8GB.
  • Reply 2 of 14
    randycat99randycat99 Posts: 1,919member
    So any idea why this requirement exists? (not, that I have a dying need to do otherwise- just curious)



    I guess there are some conditions that should be clarified:



    ?If the HD is not partitioned, then the OSX could be anywhere on the HD? (naturally it will be in the beginning on a fresh HD, but on a previously used HD, there may be stuff already on there that precludes access to the first 8 GB)



    ?other models besides the ones you mentioned above can have partitions of any size, and OSX will still install w/o trouble on any of those partitions (assuming the storage size is appropriate)? There is no significance to the specification of 8 GB, in that case?
  • Reply 3 of 14
    kickahakickaha Posts: 8,760member
    Quote:

    Originally posted by Randycat99

    So any idea why this requirement exists? (not, that I have a dying need to do otherwise- just curious)



    I guess there are some conditions that should be clarified:



    ?If the HD is not partitioned, then the OSX could be anywhere on the HD? (naturally it will be in the beginning on a fresh HD, but on a previously used HD, there may be stuff already on there that precludes access to the first 8 GB)




    No. On the Beige G3s, the OS *must* be installed in a partition that is *no larger* that 8GB, and *must* be first on the drive. It is a limitation of the drive controller on the motherboard.



    Quote:

    ?other models besides the ones you mentioned above can have partitions of any size, and OSX will still install w/o trouble on any of those partitions (assuming the storage size is appropriate)? There is no significance to the specification of 8 GB, in that case?



    Correct. This only affects the Beige G3s.



    And maybe the Bondi iMacs.
  • Reply 4 of 14
    randycat99randycat99 Posts: 1,919member
    Ok, thanks!
  • Reply 5 of 14
    scottscott Posts: 7,431member
    My Lime iMac has this limitation. My understanding was that the partition could be any size but the bootable OS had to go in the first 8 Gigs. It has to do with the address that's held in firmware for the location of the OS on the disk if I remember. When I installed dual boot linux and Mac OS 9 I had to cram them in there. It left me with a large user partition on the end of the drive.
  • Reply 6 of 14
    cosmocosmo Posts: 662member
    This issue is present in all gen 1 iMacs (tray loading).

    233, 266 and 333mhz models are affected.
  • Reply 7 of 14
    randycat99randycat99 Posts: 1,919member
    I luv u guys.
  • Reply 8 of 14
    xoolxool Posts: 2,460member
    For the record, you can partition a large drive in to multiple segments. Any partition that resides solely within the first 8 GB on the drive can be bootable. This means you could have 2 bootable 4 GB partitions, or 1 bootable 8 GB partition.



    I have used this technique on both Beige G3s and tray-loading iMacs.



    I am pretty certain that this only applies to the built-in IDE controller. If you use a SCSI card and drives you can sidestep this issue. That doesn't really help the iMacs though.
  • Reply 9 of 14
    paulppaulp Posts: 67member
    Quote:

    Originally posted by Cosmo

    This issue is present in all gen 1 iMacs (tray loading).

    233, 266 and 333mhz models are affected.




    I found that 'installing' OS X does require an initial 8gb partition, but by restoring an existing disk image using the Restore tab in Disk Utility or, even better, Carbon Copy Clone the full disk size is available.
  • Reply 10 of 14
    randycat99randycat99 Posts: 1,919member
    Interesting solutions, guys!
  • Reply 11 of 14
    jkbjkb Posts: 18member
    The first 8G issue is related to the ROM/Open Firmware in older machines. Basically, they don't understand, properly, an OS outside of the first 8Gs.



    Another trick, which I've had repeated success with, is not to format the partition as 8G, but 7.99G. Sounds silly, but works every time.



    jkb
  • Reply 12 of 14
    randycat99randycat99 Posts: 1,919member
    Is the idea there that you can then install OSX beginning of the next partition since that first .1 GB still lies within the 8 GB addressing requirement in the firmware? All that is really needed is to be able to point to a boot location within the first 8 GB rather than having to fit the entire OS installation in the first 8 GB?
  • Reply 13 of 14
    xoolxool Posts: 2,460member
    If you can ensure that the entire OS installation resides within the first 8 GB of the drive, these rev A machines will boot fine. However, if a system file gets relocated beyond the first 8 GB the machine will suddenly not be able to boot. This is why Apple disables installation on these partitions, so that this situation doesn't occur.



    I suggest partitioning the drive in to an 8 GB OS slice and another slice for data. You can even relocate your Users directory there with a bit of work.
  • Reply 14 of 14
    pbpb Posts: 4,231member
    Quote:

    Originally posted by Cosmo

    This issue is present in all gen 1 iMacs (tray loading).

    233, 266 and 333mhz models are affected.




    Count the Wallstreet Powerbooks too. The situation changed from the Lombard Powerbooks.
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