TITLE
    Macintosh Operating System: Maximum Volume Size
Article ID:
Created:
Modified: 		11333
1/27/93
8/18/98
TOPIC

    We have been seeing some strange results when trying to use volumes larger than 2 GB. What is the maximum volume size supported by the Macintosh operating system?

DISCUSSION

    A set of modifications to the Finder and HFS were implemented to raise the maximum volume size of 2 GB to 4 GB. This was done by treating volume sizes as unsigned values. The exact upper limit is 4063 MB. System 7.5.2 (and newer) increases this limit to 2 terabytes on some computers, including:
    • any system that shipped with System 7.5.2 or newer.
    • any Macintosh system with PCI slots.

    It is not necessary to have SCSI Manager 4.3 installed to take advantage of the larger volume sizes.

    Note that AppleShare, including Personal File Sharing, has its own volume size limitations. For more information, please see the following Tech Info Library article:

    Article 15460: " AppleShare File Server: Chart Of All Limitations "

    With versions of the Macintosh operating system previous to System 7.5 we recommend making the volume sizes slightly less than 2 GB to ensure that you do not run into any limitations.

    This means that if you have a hard disk drive with a formatted capacity larger than the 2 GB, you must partition it into multiple volumes smaller than 2 GB. We have found that a partition size at least 1 MB smaller than 2 GB seems to work acceptably.

    Possible symptoms of volumes equal to, or larger than the 2 GB limit include:
    • Negative file sizes
    • Inability to copy files because "More space is needed" even though plenty of space is available.
    • Similar symptoms on Novell (or other) servers when the volumes published over the network are larger than 2 GB.

    This is a hard limitation. There are no workarounds other than partitioning the drive into multiple volumes or updating your computer and any client computers that may log on to the volume to System 7.5.x or newer.

Document Information
Product Area: Mac OS System Software
Category: General OS
Sub Category: General Topics

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