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Special Notes About Large Hard Disks

Article ID = 56
Article Title = Special Notes About Large Hard Disks
Article Author(s) = Graham Needham (BH)
Article Created On = 7th October 2011
Article Last Updated = 10th September 2014
Article URL = http://www.macstrategy.com/article.php?56

Article Brief Description:
Information about using large / advanced format technology / SATA 3 hard disks

Drives larger than 2TB

macOS / OS X / Mac OS X HFS+ supports "volumes" larger than 2TB:
  • Maximum volume size and file size (Mac OS X 10.0 - 10.1.5) = 2TB†
  • Maximum volume size and file size (Mac OS X 10.2 - 10.2.8) = 8TB†
  • Maximum volume size and file size (Mac OS X 10.3 - 10.3.9) = 16TB†
  • Maximum volume size and file size (Mac OS X 10.4 or later) = close to 8EB (ExaBytes)†
† = The theoretical maximum file size for a Mac OS Extended file system is millions of terabytes. In practice, the maximum file size is equivalent to the maximum volume size, except for a small amount of disk space reserved for file system information.
NOTE: However, now that individual physical hard disks have surpassed 2TB in size hardware factors can come into play in being able to use such drives. See the AFT and SATA 3 notes below.

More information on using hard disks larger than 2TB from the manufacturers themselves:

Advanced Format Technology (AFT) Drives

Due to increasingly large capacities of hard disks (usually those above 2TB) some drives now use Advanced Format 4K sector technology. AFT can easily be incompatible with older versions of macOS / OS X / Mac OS X and hardware (both Apple and third party). In theory Mac OS X 10.4 onwards supports AFT but in reality this is not always the case:
  • Mac OS X 10.3 and earlier - do not support AFT
  • Mac OS X 10.4 - both PowerPC and Intel Macs appear to have issues with AFT
  • Mac OS X 10.5 - PowerPC Macs have issues with AFT but Intel Macs seem to be okay
  • Mac OS X 10.6 or later - support AFT
NOTE: In all cases GUID partition format must be used.

Your next issue is the hardware chain:
  • Built-in internal SATA ports (silver Mac Pros) seem to support AFT
  • Built-in internal SATA ports (Xserve) do not seem to support AFT
  • Built-in internal SATA ports (PowerMac G5) many issues reported usually with one or both of the drive bays
  • Apple hardware RAID card (for silver Mac Pro) does not seem to support AFT
  • THIRD PARTY PRODUCTS: Always check with your manufacturer that the product is AFT compatible especially:
    • Internal SATA cards both SATA and/or eSATA
    • hard disk enclosures taking SATA hard disks
    • tray free hard disk enclosures/drive docks taking SATA hard disks
    • RAID boxes taking SATA hard disks
    • SATA hard disk trays and sleds e.g. Xserve Apple Drive Modules (ADM)
    • computers with internal SATA ports e.g. Mac Pro (Silver), modern Xserves, modern iMacs
    • PCMCIA / PC card to eSATA adaptors
    • Express34/54 card to eSATA adaptors
    • SATA hard disk adaptors e.g. Wiebetech DriveDocks / Drive eRazers / Forensic docks or NewerTech Universal Drive Adapters
More information on using AFT drives from the manufacturers themselves: Look out for this logo on the hard disks/your hardware:

SATA 3 6Gb/s technology

SATA 3 technology is a new faster data bus technology primarily used for storage devices such as hard disks and solid state devices (SSDs). In most cases it is backwards compatible with older SATA 1 and SATA 2 hardware but not always. Most SATA 3 hard disks have drive "jumpers" on them that allow you to jumper the device and throttle it back to SATA 2 or 1 compatibility when required.
NOTE: As of late 2011, rotational media i.e. hard disks (HDDs) not solid state disks (SSDs ) cannot actually read/write at 6Gb/s speeds anyway.
Look out for this logo on the hard disks/your hardware:

Article Keywords: Mac OS X OSX 102 103 104 105 106 107 108 109 1010 1011 macOS 1012 1013 Jaguar Panther Tiger Leopard Snow Leopard Lion Mountain Lion Mavericks Yosemite El Capitan Sierra High Sierra AFT Advanced Format Technology eSATA SATA 3 III 6Gb/s 6Gbps 2TB 2.5TB 3TB 4TB 5TB 6TB 8TB 10TB Macintosh

This article is © MacStrategy » a trading name of Burning Helix. Apple, the Apple logo, and Mac are trademarks of Apple Inc., registered in the U.S. and other countries. App Store is a service mark of Apple Inc.


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