How to remount an internal drive as read-write in mountain lion

Question

Suddenly a secondary drive with HFS+ partition changed from read-write to read-only. How can I use the mount command to reverse it in mountain lion?

score 18 · Answer 1 · edited Jun 03 '13 at 07:45

18

Try using mount -u -w:

sudo mount -u -w /Volumes/YourDriveName

-u modifies the status of an already mounted filesystem. -w mounts a filesystem as read-write.

edited Jun 03 '13 at 07:45

Lri

105,117

answered Jun 03 '13 at 04:46

TJ Luoma

20,659

2

mount_hfs: Invalid argument. – 2rs2ts Jan 03 '16 at 19:20
1

If it's ntfs you may need a few more params than that: https://apple.stackexchange.com/questions/20889/how-do-i-write-to-ntfs-drives-in-os-x and also you may need to unmount then remount to avoid "Read Only Drive" message... – rogerdpack Sep 28 '18 at 19:03
Is there any way to revoke write access after doing this? – Noldorin Dec 07 '19 at 00:44
You’d have to unmount the drive and re-mount it as read-only. – TJ Luoma Dec 07 '19 at 02:06

score 7 · Answer 2 · answered Oct 03 '16 at 17:14

7

The answers in this thread did not work for me, but this did:

  sudo mount -u -o rw /Volumes/VolName

answered Oct 03 '16 at 17:14

user204422

71

same error as above for me – Sridhar Sarnobat Jul 28 '20 at 04:19
Somewhat strangely, I had to run above command twice for it to work. – Blindfreddy Oct 19 '21 at 07:54

score 2 · Answer 3 · answered Jun 03 '15 at 16:14

Occassionaly when this happens to me I need to use the disk utility included with OSX to verify and repair the disk. Any attempts to use mount -u -w /Volume/NIKON-S9700 will fail with this error:

$ sudo mount -u -w "/Volumes/NIKON-S9700"
mount_msdos: /dev/disk2s1 on /Volumes/NIKON-S9700: Permission denied

You can tell that the disk is mounted read-only like so:

$ mount
/dev/disk1 on / (hfs, local, journaled)
devfs on /dev (devfs, local, nobrowse)
map -hosts on /net (autofs, nosuid, automounted, nobrowse)
map auto_home on /home (autofs, automounted, nobrowse)
/dev/disk2s1 on /Volumes/NIKON-S9700 (msdos, local, nodev, nosuid, read-only, noowners)

NOTE: Notice the "read-only" in the output above for device /dev/disk2s1.

Once I run a repair disk from Disk Utility the drive when mounted shows up like this:

$ mount
/dev/disk1 on / (hfs, local, journaled)
devfs on /dev (devfs, local, nobrowse)
map -hosts on /net (autofs, nosuid, automounted, nobrowse)
map auto_home on /home (autofs, automounted, nobrowse)
/dev/disk2s1 on /Volumes/NIKON-S9700 (msdos, local, nodev, nosuid, noowners)

Incidentally the repair disk button might sometimes show up as grayed out. I typically have to unmount and remount the disk with Disk Utility running in order to get this button to show up as clickable.

screenshot of Disk Utility with mounted SD Card

ss#1

score 2 · Answer 4 · answered Jun 03 '13 at 15:04

2

This happens sometimes when a drives filesystem is corrupted. Run Disk Utility and check the filesystem and drive for errors.

answered Jun 03 '13 at 15:04

BMorgenthaler

121

score 1 · Answer 5 · answered Aug 22 '20 at 04:16

1

This was silly, but after a bunch of troubleshooting, for me the problem was that I was dealing with an sd card that had its lock switch turned on. I ejected the disk, toggled the switch, re-inserted it, and it was back to read+write.

answered Aug 22 '20 at 04:16

Xiong Chiamiov

425

How to remount an internal drive as read-write in mountain lion

5 Answers5

screenshot of Disk Utility with mounted SD Card

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