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Why is my Mac hard drive suddenly read-only?

Hi Dave, I am running Mac OS X 10.3.9 and recently encountered a strange occurrence. Instead of the usual tag under my main hard drive(74.4 GB, 24.75 GB used) it shows (74.4 GB). After I used "Get Info" it says i have read-only access. Every time i want to move a file to it, it asks for my admin password. I am normally an admin user, and this has never happened before. Is this a major thing? And how can i change it back to what it was before?

Dave's Answer:

That's a very strange occurrence, I agree with you. The good news is that one of the standard administrative applications included with Mac OS X will doubtless fix what's happened on your disk, which is that a folder permission has somehow been messed up.

The program you need is Disk Utility and you can find it in Applications --> Utilities --> Disk Utility. Then simply select the drive you want to fix:

Click for full size screenshot

In this case, "X" is my boot drive, and "X2" is my backup drive. I clicked on the "X" drive, then on the button Repair Disk Permissions.

Now the utility will go through the entire file system, making sure that the access permissions and ownership of each major directory matches the recommended configuration from Apple. It'll take a few minutes, during which time you'll see information like:

Finally, it'll be done and I bet your problem will be fixed!

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Categorized: Mac OS X Help (Article 6396)
Tagged: disk troubleshooting, mac os x, repairing permissions
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Comments

I tried this and it didn't work. Not complaining, I appreciate free advice, but I though you'd like to know.

Posted by: paul miller at June 9, 2006 6:59 AM

I have an external hard disk drive that is 400gb and it says read only for the mac but it lets me edit files on it on my pc!? Any help would be really appreciated.

Posted by: Oliver Tappin at April 25, 2007 1:00 PM

Hello there, i agree with davem you do need to format it but its also to do with fat32 and NFTS! Macintosh computers only work woth fat32 and windows have come up with their one that they have made which is much faster which is called NFTS. If you want to use your external hdd with mac and pc, then you need to format it on the mac, which will automaticly put it to fat32 but if you format it on pc, make sure it is set to fat32 and NOT NFTS. NFTS only works with windows, even though its really fast and works well, fat32 works with mac and pc. If you have any problems, i would be happy to help. Hope that helps anyone here!

Posted by: Ollie at May 20, 2007 11:59 AM

i can no find my hard drive
my hard drive is lost

Posted by: roberto at May 30, 2007 10:03 PM

Is there a way of making it FAT32 without loosing all your data on the hard drive?

Posted by: Matt at August 15, 2007 7:27 AM

Hi,

I have the exact same problem,
My 'Repair disc permissions' is greyed out..

Any Ideas..?

Posted by: Mike at January 24, 2008 2:13 PM

Hi ,I am Aditya from India .I have a problem that I am unable to solve and know the root cause.My system stops suddenly (while browsing ,listening music ...etc)i.e just like a movie been paused ,then i restart my system using power switch.It just shows a blank screen and my hard disk makes a kink sound at the beginning and then it goes on reading and reading but blank screen remains.
My details: Motherboard Intel 915GAV ,
Processor Intel 2.8GHz HT, HDD :Seagate Sata ST3160215AS_____________________________3.AAD___\5&30D26B9&0&0.0.0
RAM: 512MB . OS :XP+sp2
3 years old and motherboard been replaced twice due to above reason.
I have removed my cables and then reconnected and the problem is solved ,but at times I have to reconnect more than 10 times and even 2 days .Then it starting booting and starts normally .I am unable to know the root cause .I am regularly installing latest OS after 6 months.

Posted by: Aditya at January 25, 2008 9:08 AM

This was all great, until the Restore button was greyed out.

Your advice was simple and clear, just left me at a dead end.

You can email an answer if you figure it out at rswild@gmail.com

Thanks,

Scott Wild

Posted by: Scott Wild at February 12, 2008 10:49 AM

FYI fat32 is only good for 2 gigs

but on the reformating thing...windows only lets mac read its files (nfts), not write...that includes washing it down(for older systems anyway)...ik i can on leopard...

but for sharing..well i like to keep my dirty mp3s on the mac cuz it can take it, analog record to windows and save on a dif partition on my exhd...then ik its clean 4 good lol

but yea...discs work 2

Posted by: david at February 23, 2009 1:50 PM

What David REALLY meant to say is that fat32 is only good up to 4 gigs PER FILE( NOT PARTITION!)

Otherwise anyone that buys a Western Digital portable hard drive will be confused why their 100+ gig hdd is fat32...

But I did find these comments useful. Didn't know ntfs(not nfts, as others put it lol) wasn't writeable on a Mac. It confused me because it works in both Windows and Linux... in Linux it shows that my hdd has 777 file permissions, but when I mounted it on my Mac it only had 755.

Posted by: Ryan at March 21, 2009 2:17 PM

hi!

i have a problem... I was trying to lock my macintosh hd and accidentally placed read only for the admin then locked it. i later realised what a disaster it was and decided to restart my laptop. when i turned it on the screen was blank and just loading for almost an hour. i repeatedly restarted it for the day but it wont go to the actual desktop. my laptop has a login and password requirement to get to the desktop. please help me!thanks

Posted by: j at May 9, 2009 4:31 PM

Hi Dave,

I have the Final Cut Express 4 software on my imac.Have tried to configure my external drive but am getting the message "unable to set scratch disc.the selected directory is on write protected or non-writable media"
How can I go about configuring it? A step by step explanation will be appreciated very much.

Bernard

Posted by: Bernard at June 26, 2009 6:18 AM

I just wanted to add how to do this from the terminal since this site gets all kinds of hits

Machine will not load OS. Reboot
While starting up hold APPLE-S until you see it in a command prompt.

Follow the instructions provided to mount your Volume (doesn't work unless you mount it;)

Now follow the rest:

Type
cd /Volumes
and press enter

Type the command
chmod 755 Macintosh\ HD/
and press enter

sudo chmod -RN /Volumes/"Macintosh HD"/Users/USERNAME
sudo chown -R USERNAME /Volumes/"Macintosh HD"/Users/USERNAME

Please share this with everyone, it's worked a dozen times for me. Apple needs to make it so that we can't mess up an OS from the preferences pane.

Posted by: another dave at November 3, 2009 9:18 AM

i have mac osx tiger and my ibook g4 keeps going into the single-user mode and im not able to get it out of there and start my laptop normally how do i get out of this and make sure it does not go back in there?

Posted by: Milton Herrera at November 10, 2009 4:59 PM

I have something to say, now that you mention it, but ...

I do have a lot to say, and questions of my own for that matter, but first I'd like to say thank you for all your efforts on this Web site by buying you a cup of coffee!

I do have a comment, now that you mention it!