can't get writeable access to an external HD...

Discussion in 'MacBook Pro' started by maya90, Apr 8, 2015.

  1. maya90, Apr 8, 2015
    Last edited: Apr 8, 2015

    maya90 macrumors member

    Feb 16, 2011
    I have a typical WD external hard drive... it was writeable before, but now, because I had been using it for backup on a windows machine, it's read-only... but I won't be using it for the backup on that windows machine anymore, so need to make it writeable again.. have not found a way to do this on my mac...

    so it occurred to me I had to connect it again to the windows machine where I had been doing the backup to make it writeable again.. and indeed on that machine I was able to remove the contents np, and save a file to it (& rename the HD..) but when I connected it to my mac again I was again denied write-access.. it remains read-only on my mac... how do I make it writeable on my mac, please (I'm on 10.6.8..)
    (do I maybe need to do it in unix? what would be the command(s)? I can't find a way to format it on the mac.. (on windows you right-click on it and one option is "format", I see no such option on the mac when I right-click on it..)

    thank you...
  2. GGJstudios macrumors Westmere


    May 16, 2008
    What is the drive format? If the format of the drive is NTFS, OS X does not write to that format natively.

    Format A Hard Drive Using Disk Utility (which is in your /Applications/Utilities folder)
    Choose the appropriate format:
    HFS+ (Hierarchical File System, a.k.a. Mac OS Extended (Journaled) Don't use case-sensitive) NTFS (Windows NT File System)
    • Read/Write NTFS from native Windows.
    • Read only NTFS from native Mac OS X [*]To Read/Write/Format NTFS from Mac OS X, here are some alternatives:
      • For Mac OS X 10.4 or later (32 or 64-bit), install Paragon (approx $20) (Best Choice for Lion and later)
      • For 32-bit Mac OS X, install NTFS-3G for Mac OS X (free) (does not work in 64-bit mode)
      • For 64-bit Snow Leopard, read this: MacFUSE for 64-bit Snow Leopard
      • Some have reported problems using Tuxera (approx $36).
      • Native NTFS support can be enabled in Snow Leopard and Lion, but is not advisable, due to instability.
    • AirPort Extreme (802.11n) and Time Capsule do not support NTFS
    • Maximum file size: 16 TB
    • Maximum volume size: 256TB
    • You can use this format if you routinely share a drive with multiple Windows systems.
    exFAT (FAT64)
    • Supported in Mac OS X only in 10.6.5 or later.
    • Not all Windows versions support exFAT. See disadvantages.
    • exFAT (Extended File Allocation Table)
    • AirPort Extreme (802.11n) and Time Capsule do not support exFAT
    • Maximum file size: 16 EiB
    • Maximum volume size: 64 ZiB
    • You can use this format if it is supported by all computers with which you intend to share the drive. See "disadvantages" for details.
    FAT32 (File Allocation Table)
    • Read/Write FAT32 from both native Windows and native Mac OS X. [*]Maximum file size: 4GB.
    • Maximum volume size: 2TB
    • You can use this format if you share the drive between Mac OS X and Windows computers and have no files larger than 4GB.
  3. redheeler macrumors 603


    Oct 17, 2014
    You can format the drive in Disk Utility. Select it in the sidebar and click the Erase tab. You can format it as "ExFat" for use with both Mac and Windows or "Mac OS Extended (Journaled)" for use on the Mac.
  4. dyt1983, Apr 8, 2015
    Last edited: Jun 2, 2015

    dyt1983 macrumors 65816

    May 6, 2014
    edit: To remove personally identifying information not relevant to the thread.
  5. maya90 thread starter macrumors member

    Feb 16, 2011
    thank you very much for that lengthy response!!
    (& thank you to the other responders...)

    that worked!! (had not thought of disk utility... I knew I was missing something fundamental, just couldn't think of what... erased it in two mins..)

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