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Special Considerations for Partitioning on Mac OS X
(KB # 3DC066DA)

This article is specific to Mac OS X 3TB partitioning considerations. For more information about 3TB cartridge partitioning on Windows, please see also the Windows related KB article.

Parititioning for Interchange

When Mac OS X Finder is used to "Erase" a large cartridge and re-partition, the disk format written by Mac OS X is generally not readable on Windows systems. This can be important if the cartridge is to be used for interchange between Windows and Mac OS systems.

To re-partition a cartridge for use with Mac OS X and Windows interchange, please either:

1) Use the instructions in the Windows related KB article


2) Use the instructions below and choose the ExFat format.

Partitioning for use on Mac OSX Only

Attempting to reformat an RDX cartridge for use on Mac OSX you may notice errors "Not enough space on requested device" or "Invalid Request" when attempting to re-partition or re-format through time machine preferences or the Disk Management utility. To successfully format and partition the cartridge, follow the instructions below.

Please note: Any data on the cartridge will be permanently lost.

  1. Open the Disk Utility application
  2. Select the RDX cartridge. Note that partitions on the RDX disk may be listed below the RDX disk. The RDX disk should be selected, not the partitions.
  3. Select the “Erase” button on the top of the Disk Utility.
  4. In the window for choosing the erase options choose your cartridge's new Name, Format and Scheme. Press Erase button when you're ready to reformat the cartridge
    • For cartridges 2TB in size or larger, ensure “GUID Partition Map” Scheme is selected
    • ExFAT is a convenient format for exchanging data with Windows, Linux, and Macintosh systems.
    • Other formats are fine if the disk will only be used on Macintosh systems.

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