External Hard Drives Changing Permissions to Read Only

Oldguy

I had the same problem.

I ignored Kappy because he just enjoys abusing people and not helping, just sitting on his little throne throwing barbs.

The verify disk option in the built in Disk Utility fixed the problem for me. Hope it fixes it for you too.

Thanks for the tips. Verifying at Disc Utilities helped for me as well. At first though it said that I had to restore the HD, which I didn't want to do for I didn't know what the consequences would be. Then I closed the program and opened it again for I was curious what it would say now. But then it said nothing about restoring anything and I found out I could write again on the HD. Good luck everyone. Thanks again.

I am (have been) having this same issue for over a month. I have three hard drives on my iMac. 500 GB Internal HD, 1 2 TB External asting as a Time Machine Backup, and 1 2 YB External with Lion installed, along with tons of music, apps, data files etc. These have all been working fine the last week or so since the mysterious Read Only locks at least two of my three disks (not always the same ones). I have done all the standard stuff, Disk Utility to Repair the Disks, running Repair Permissions, a couple of times even going into the Terminal and going through the Repair Home Folder Permissions routine. I'm never sure what fixes the problem, only that as suddenly as it starts, it goes away the next day or so.

Tonight, Time Machine is Read Only... AGAIN, and my Lion Hard Drive is ALSO Read Only... AGAIN.

I ran through the SAME proceedure on these two hard drives tonight - 1.) Disk Utility, Click the drive in question in the Left Column in Disk Utility, then choose Repair in the Right Column. That completed, I ran Repair Permissions. Did the SAME to both disks. Time Machine is now BACK and writeable again, but the other HD is still Read Only.

I'm going to Shutdown, Reboot, and check the Permissions again...

After I Shutdown and re-Booted, the Lion HD showed up greyed out in Get Info - could do NOTHING with it, Disk Utility, etc. Noted that each time I've had these issues, my iPhone 4 is always plugged in also (I take advantage of my time on the iMac to re-charge the iPhone battery). On a lark, I un-plugged the iPhone and it's cable from the iMac. No change. The Lion HD was showing up in Disk Utility as greyed out as I said earlier. For the heck of it, I used Disk Utility to UNMOUNT the Lion HD, then used Disk Utility to Mount it again... it immediately showed up as available in the Disk Utility, went ahead and just ran Repair Permissions (before I checked the Read / Write permissions) and when it finished repairing permissions, I checked permissions again, and IT IS BACK IN THE LAND OF THE LIVING, Sharing & Permissions in Get Info once again say "You can read and write"...

Now, WHY does it do this (as it happens at least a couple times a week? DOES the fact that the iPhone is plugged in have something to do with it? Something to watch for I guess...

The problem may be an erroneous flag for the volume of the external drive that puts it in read-only mode. When I had a similar problem, the following steps corrected it.

1. Open Disk Utility and Verify the Volume.

2. If the verification shows that the volume is OK. If so, run repair disk. If the verification does not show that the volume is OK, STOP. Copy the drive immediately to another drive before proceeding. Failure to do so can result in permanent data loss.

3. After the repair function completes, close Disk Utility and check the status of the volume. Running verify or verify and disk repair didn't fix the problem for me. If your volume still shows that it is read only, start Terminal. It is located in the System Utilities. Type in the following command follwed by the name of the affected volume:

sudo chflags nouchg /Volumes/[Volume Name]

For example, assume your external drives are named Mary X where X is a sequential Arabic numeral. The command line for one of those volumes will be "sudo chflags nouchg /Volumes/Mary\ X" where X is the drive number. You will be prompted for your administrator's password. Note that when you type in the password, it will not be echoed in the terminal window for security reasons . Press "Return"

If your experience is similar to mine, your external drive will no longer be in read-only mode. Hope this is helpful.

I couldn't figure out how to do this either, but then I found the eHow page for it!

http://www.ehow.com/how_5103741_reformat-flash-drive-mac.html

This works! it's great 😀 It's really simple - just go into 'utilities' -> 'disk utility' -> 'erase' -> then it should be all good

N.B. Before you 'erase' they external drive, make sure you have a copy of the files elsewhere, otherwise they will be 'erased'

HWNewbie - I know I am like 18 months past this post date however I did the verify disk and surprisse surprise, it actually changed my permissions. It states "You can read and write". Thank you so much.

Hi, hope this help. Go to Seagate and download:

NTFS Driver for Mac OS

The NTFS Driver (5MB) allows you to mount the NTFS partition on both a GoFlex and Backup Plus drive as read and write (NTFS would normally be read only in MacOS), so the drive can be used to drag and drop files between a computer running Mac OS and one running Windows.

This will solved your problem.

I have the same problem, but with more problems added to it:

I'm a noob to so I'll try to cover all the details

My EHD was working untill recently

Worked in both Windows and Mac

is formatted in MS-DOS FAT32

The added problem is that it keeps ejecting and connecting. When I tried backing up, copy window froze, then closed, prompted another one saying some data cannot be read and finder window closed. HD disappeared from desktop and then reappeared. So I cannot backup my info.

Tried the ** verify, stopped midway and shows a message saying ** stopped verifying HD click repair disk. Meanwhile HD ejected and connected again, and the option for repairing disk is not active, so this did not work. Also I cannot edit anything on the erase or partition tabs, but the Raid and restore tabs are available.

Tried opening Info and all I can edit is the shared folder option, name and extension are blocked and the permissions tab says "You can only read" nothing more.

I don't want to format my HD because I NEED to backup my info.

Any help will be greately appreciated.

A suggestion I'd like to offer is go to your System Preferences and open Sharing. In that window, you can click on each Service (the name, not the checkbox) and you'll see the permissions for each kind of device. In the cases of these postings, click on File Sharing and you'll see your connected hard drives and other storage with their corresponding permissions.

This is where things can get a little weird. A couple of years ago I transferred a bunch (as in GB's) of old files from a couple of old antiquated hard drives onto a new drive I'd just purchased. Things went well for a while then all of a sudden I had difficulty accessing it. I checked the permissions described above and was amazed to discover there were new additional users and those and the other users had an array of priveldges; some Read Only, some Write Only, some No Access, etc. Using the + and - , I mirrored the permissions of other connected hard drives I had. After restarting everything, the drive ran without problem.

My guess is the plethora of files I'd transferred from those old drives, some formatted FAT, had somehow screwed up the permissions.

This may or may not cure everyone else's problems, but it might be something to check out when you run into a problem.

I'd really like to see Apple rewrite its Disk Utility to allow for the repairing of permissions on files and drives other than boot drives. You should be aware that the utility doesn't fix permissions of files on boot drives that aren't directly related to the operation of the computer. I think this is crazy. Allowing Disk Utility to fix these issues would go a long way towards fulfilling their policy of providing users with a good experience.

This problem occurs whenever you DONT unmount your usb flash/drive from Windows properly. NTFS being smart filesystem locks itself up, so MAC will mount it read-only. That's when the "check" or "repair" trick works.

memarc123, please be more specific. When you say you can't use the verify button, is it the Verify Permissions or Verify Disk?

If it's Verify Permissions, you can only verify the permissions of your startup disk, usually the hard drive of your computer.

If it's Verify Disk, you can verify any disk that's mounted. Just make sure you're selecting the disk's partition and not the disk itself. For example, a disk might be listed as Toshiba_HD4759-66 but that drive had to be formatted to be used and will have a name immediately below, for example MyExternalHD. You have to be sure to select the latter name to effectively verify the disk structure.

Thank you so very much 'Itzawrap'. I reformatted my external so I could upgrade my iMac to Maverick and experienced 'read only.' I experienced the vapors BIG TIME. I did exactly as you wrote and repaired my external, and the result is now it is back to 'read & write.' Thank you for taking time to post this. My vapors have vaporized. Thank you.

HWNewbie wrote:

I am sorry I seem to have upset you by my response! However, your abuse is completely uncalled for and I am afraid I will have to report you for the abuse. You have also been abusive and bullying to another person on the discussion board.

My solution worked for me and it is a pity all your four or so posts were - how should I put it - less than helpful.

I'm on an iMac, not a MacBook Pro, but your solution worked exactly the same way for me, too, so I really appreciate your posting this. It was a terrifying few moments. My two crucial external drives have worked fine for a long time and then suddenly became "Read only" with no rhyme nor reason. I found your post and as a long shot tried it. DiskUtility reported that they both were fine—and then suddenly the permissions were not grayed out any more in the Info window, and their windows didn't have the crossed-out pencil down in the lower left corner any more.

I don't know why the guy was so abusive to you, but maybe he should pay attention to what happens in the real world.

I am having the same issue.

Enriques-MacBook-Pro:~ ENRIQUE$ ls -l /Volumes

total 8

drwxrwxrwx 0 root wheel 0 Oct 28 14:43 MobileBackups

drwxrwxrwx 22 root wheel 1768 Oct 28 11:54 TOSHIBA

lrwxr-xr-x 1 root admin 1 Oct 28 13:57 Untitled -> /

These are my results.

I can't seem to make it work.