Previous 1 2 Next 18 Replies Latest reply: Aug 19, 2014 10:35 AM by BDAqua
jinc07 Level 1 Level 1 (0 points)

Hello all,


I'm fairly new to the Mac world, so please go easy on me. I've been having trouble with an external hard drive I've been sharing between a PC and Mac.


I bought a 1TB Western Digital external hard drive a while back and I partitioned the drive into 2 portions - one that was formatted NTFS and one that was formatted Mac OS Extended (Journaled). I have MacDrive on my PC, which runs Windows 7, so I can read/write on both formats.


The problem arose when a few days ago I found I couldn't write to the Mac formatted portion of the hard drive from my Mac Book Pro. I can still access and write to both portions when I use my PC, so I figure it's something that happened or changed on the Mac. I've searched around a little for help on this problem, but the majority of answers seem to be with changing the permission on the hard drive. The thing is, when I use "Get Info" on the Mac formatted portion, I can't change the permissions (they're all greyed out and unclickable). I'm stumped as I've exhausted my knowledge of the workings of the Mac machine.


Is there anything I can do to fix this?


For reference, my Mac Book Pro is running Mac OS X 10.5.8.

MacBook Pro, Mac OS X (10.5.8)
  • BDAqua Level 10 Level 10 (121,185 points)

    Hello, & a warm welcome to the forums & Macdom.


    When you do a Get Info on that Mac Partition, can you unlock the lock at the bottom? Is there an ignore Permission on this Volume check box? What are the grayed out permissions staing anyway?

  • jinc07 Level 1 Level 1 (0 points)



    Thanks for the welcome!


    When I do a Get Info, I can indeed see a lock at the bottom and some permissions. The lock is unclickable, and the grayed out permissions are as below:


    You can only read.

    Me - Read & Write

    staff - Read & Write

    everyone - Read Only

    The "Ignore owenership on this Volume" box is checked, but grayed out.


    That's pretty much all the information under the "Sharing & Permissions" section.

  • BDAqua Level 10 Level 10 (121,185 points)

    Open Terminal & paste this in, spaces are important...


    chown root /Volumes/


    chmod 1777 /Volumes/


    then right after the last / of each line, carefully type the name of that external volume, & if it has spaces in it enclose the name in quote marks.


    See this User Tip by Niel: I accidentally set a disk's permissions to No Access ...

    If the disk in question is your Mac OS X startup disk and your computer stops starting up at the blue screen, restart with the Command and S keys held down, and enter the following commands:


    mount -uw /

    chown root /

    chmod 1775 /



  • jinc07 Level 1 Level 1 (0 points)

    I've tried your suggestions in Terminal, but I get the following result:


    chown: /Volume/volumname: operation not permitted

    chmod: /Volume/volumname: read-only file system


    Is there a certain way of doing this? I've never used the Terminal before.

    Thanks for all your help so far.

  • BDAqua Level 10 Level 10 (121,185 points)

    Did the mount command work?


    And was volume name the Mac Partition?

  • jinc07 Level 1 Level 1 (0 points)

    Yes, the volumename is the Mac partition. I've actually named it "Mac" to distinguish it from the NTFS Partition.


    I haven't tried the mount command because it's not a startup disk and I didn't think it applied to me.


    Should I try it?

  • BDAqua Level 10 Level 10 (121,185 points)

    Yes, it has to be mounted Read & Write, that's why you got...


    operation not permitted


    read-only file system


    You cannot Write anything to a Read Only disk.

  • jinc07 Level 1 Level 1 (0 points)

    Hey BDAqua,


    I think that's done the trick. I'm not exactly sure of all the inner workings, but I'm now able to both read/write.


    Thank you so much for all your help!



  • BDAqua Level 10 Level 10 (121,185 points)

    Great to hear!

  • JDye Level 1 Level 1 (0 points)

    I have the same problem on a external drive that was original from a PC and now it is only read drive, and I want to be able to write on it, without having to reformat or loosing all my files.  


    from your explanation above I am not sure the mount comand would apply on an external hardrive and if so how would I write the comand without messing up my internal start up drive.


    mount -uw /Volumes/"BlackArmor Drive"/


    would this be the right comand to write in the Terminal?

  • BDAqua Level 10 Level 10 (121,185 points)

    That looks correct, even the 2 spaces, but I'm not sure that'll mount a Fat32 or NTFS drive, NTFS is read only as far as the OS goes anyway, but I don't think it'll hurt to try it.

  • F Creamer Level 1 Level 1 (0 points)

    My situation was similar: I had permission to read write to external drive, but not to the password protected diskimage within the drive.  Could not change privileges for disk image.


    Solution - So I did the unlock on the external drive in (Get Info), and added R W perm for Staff and Everyone - then click the gear icon at the bottom and check "apply privileges to internal volumes" or something like that.

  • maryb66 Level 1 Level 1 (0 points)

    This might help some with similar issues


    I had a You can only read, on my external hard drive and no way to unlock it (no lock was visible on get info) after a power failure, ie it wasn't ejected properly. I ejected the drive correct way, that is dragging it to trash, then pulled the USB plug out, waited a few seconds, put it back in again and then it was indexed correctly and I have all my correct permissions.



  • Groentas Level 1 Level 1 (0 points)

    I have a similar problem with my backup disk from my PC.

    I´ve tried to mount it, but with no luck.


    christians_macmini:~ CB$mount


    /dev/disk3s1 on /Volumes/Seagate Backup Plus Drive (ntfs, local, nodev, nosuid, read-only, noowners)

    christians_macmini:~ CB$ mount -uw /dev/disk3s1

    mount_ntfs: /dev/disk3s1 on /Volumes/Seagate Backup Plus Drive: Operation not permitted

    christians_macmini:~ CB$ mount -uw "/Volumes/Seagate Backup Plus Drive"

    mount_ntfs: /dev/disk3s1 on /Volumes/Seagate Backup Plus Drive: Operation not permitted


    Anybody having any good ideas?

    The disk has 4 TB, of which 1 is used.

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