Read-only FAT32 USB

I have a SanDisk 16gb USB flash drive that is formatted to FAT32 I somehow now is read only yet older files are on it. It is a shared USB for my class and since there are files on it I'm sure someone must have tampered with it. But does anyone know how to get the read/write back on the disk? I'm using a Mac to do so but I can use Windows if I need to.

But how would I repair the disk structure? And the drive has files on it that I can open. People used to be able to use it now it just appears as a disk image in the finder. And in Disk Utility the erase option is grayed out because it is protected? Do you know of any other reasoning behind this?

Similar Messages

Security: Read-only for USB and FireWire

Is there a way to secure the external data ports on a Mac so you can't write to a USB and/or FireWire drive? Obviously we need the SATA / InternalHD to be regular read/write. I've swapped out the optical drive so it is a read-only device, but it would be nice to have a solution that prevents writing to optical media as well.

I found two links that provide a solution.
http://images.apple.com/server/macosx/docs/TigerSecurity_Config021507.pdf
http://images.apple.com/server/macosx/docs/LeopardSecurity_Config20080530.pdf
I can't find the page(s) that reference these PDFs, so you have to download them directly.
Within the two documents are information about "removing support for mass storage devices" by trashing certain files (IOUSBMassStorageClass.kext for USB and IOFireWireSerialBusProtocolTransport.kext for FireWire).
One caveat seems to be that these files may be restored through system updates, so you need to write a login script (script provided in Leopard PDF) to ensure they are removed or simply be aware of the issue when installing system updates.

USB FAT32 is read only and will not format

My usb is formated as FAT32. however it is read only, and will not format. here are some screen shots:
http://gyazo.com/369a6b843d86ba0bcbd360ed89ea258c
http://gyazo.com/f07905c5b27519cbefbab29719c88702
http://gyazo.com/40d291c83b85e88c68ccc47a45b19f35
http://gyazo.com/490462fb7b280be7483048b2e485b2b8
not really sure what is wrong with it, any one have any suggestions?
i mean it cant be trash now, there has to be some program that will fix it.

Drive Partition and Format
1. Open Disk Utility in your Utilities folder.
2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Apply button and wait until the process has completed.
4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.
5. Set the format type to Mac OS Extended (Journaled.) Click on the Security button, check the button for Zero Data and click on OK to return to the Erase window.
6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.

USB drive spontaneously switches to read only

This has happened to me twice now. I have inserted a USB drive (formatted for FAT32) into Macbook. The USB drive has been fine for a while on both my Macbook and my Windows 7 computer. Then suddenly and spontaneously switched to read only while inserted into Macbook, without any action on my part. I have OS 10.8.5 installed on my Macbook Air. Anyone else have this problem?

Does your USB drive have a lock switch like SD cards? I have found that sometimes my SD cards will show the same behavior, it is because the lock switch got moved during insertion.
Also usally just ejecting and plugging in resolves the problem.
What is the brand and model of your flash drive?

FAT-32 USB Drive Read-Only

Hi there,
Suddenly my USB drive became read-only. Please help.
I am able to read the files from the USB-Drive but not write to it.
You can se from the above that the drive is in MS-DOS (FAT32) format and I can only read.
I tried formating the drive, creating partition etc among man other using Disk Utility but nothing is working.
Please help.
Thanks,
Jayesh

Can't erase it either, same error as the partition one. Changing port didn't work too.

Cant change the read only status of certain folders on my FAT32 external HD

Help someone please.
I have this external hard drive that has all of my music files on it. I was using it with my pc before but am making the difficult transition into mac land now. well over the last few months really. its not proving to be as easy as the marketing would have you believe. So anyway, i removed all the music temporarily from the drive (put it onto the pc's hard drive and a couple dvds), so that my macbook pro could reformat the external drive to FAT32 (which I hear works for both pc and mac). Then I put the music back on the external. and brought into my mac itunes library. then i noticed i couldn't add artwork to SOME of the files. it said "album artwork not modifiable". The external drive's info screen says permission is read and write. SOME of the folders are read and write, but SOME are locked to read only. When I look at the info of the folders and click on the locked box it won't unlock. I've attached the drive to a pc as well and tried to change permissions there but the pc saw all the files as read only. i can drag the folders off the external onto my mac desktop and unlock them there, but i can't even replace the locked files on the external with new the unlocked ones, because of course they are locked and can't be overwritten or thrown away. I've run repair disk permission on my mac's hard drive, I can't run it on the external (disk utility won't give me that option for the external). I've read a ton of discussions and threads and nothing seems to work or to match my unique problem.
Can someone please help me unlock my read only folders on my FAT32 external?

You are not alone...
http://discussions.apple.com/thread.jspa?threadID=1433620

Fat32 Shared from Mac - Folders Always Read Only?

I have a Mac Book Pro running 10.5.8 with a FAT32 Bootcamp Partition. I set up Windows Sharing so a computer running WIndows Vista can share this FAT32 volume on my Mac. The basic networking works fine, and I can open, edit and save C files in the Microsoft Visual C++ environment I'm using.
But, the compiler attempts to create temporary files during compilation and this fails. It complains that the folder is write protected. This is substantiated by the fact that when I show the folder properties for the folder in question, it shows "Read Only" in the "Attributes" section.
Thing is, using Notepad, I can create a new file and save it on these "read-only" folders without any errors.
So I'm mystified. Any thoughts on why the compiler wouldn't be able to create the temporary files?
Looking forward to a solution,
Mark

I am posting back here because I discovered the cause of the second problem mentioned in the above post. IE: the problem of misbehaving folders in windows.
First, some background. The folder structure is rather large and complex, so I created it using applescript and a text file with outline levels. Unfortunately, some of the outline titles (which became folder titles) ended in a space.
Apparently windows does not like folders (files too?) to end with a space. While this never affected my Mac, when I transfered the data and structure to the PC it went haywire. I did notice that the duplicate folders were not identical as I first thought, but rather were generated without the trailing space(s). Now it is just a matter of removing all the trailing spaces and it appears that windows can handle the folders.
However, every folder I put on the PC still says it is read only and I can't seem to change that. Any help?

Install on SDCard/USB stick, toggle read-only filesystem - possible?

This is something I thought about while installing Arch on an SD card earlier. You know these small switches on some SD cards that make them read-only, right?
Would it be possible to have a setup where Archlinux is installed on a rewritable storage device like an USB Stick or an SD card, where one mode of operation would be to use it like a regular, persisting Arch install (with writeable filesystem). The second mode would be to use it similar to a Live CD, not persisting any data on the storage device and using RAM instead (mounting the root filesystem as read-only).
Basically, you could boot into regular mode (perhaps by choosing a seperate entry in GRUB), change configurations, update packages, etc. Then you reboot into read-only mode and use it as a Live CD with any changes to the filesystem stored only in RAM. This could be combined with system encryption to provide a secure and portable Arch installation that can be kept up-to date and simply by rebooting, you have a protected, volatile environment similar to a Live CD.
Is something like that possible? Has it been done already?

Comment on the "why" for Flash Device....quiet operation, less power required, faster performance and reduced size.
Faster boot time is also possible with raid applied.
As previously stated, running all in ram doesn't provide any performance improvement if the system has at least 2GB of ram. Thus the use of swap is not required with that much ram.
This principle also applies to Flash Devices which have algortithms controlling the writes across the entire card capacity such that larger capacity increases lifetime expectancy.
Copy- on- write is also proposed for flash devices which reduces the process steps for writing to flash.
In my experience with running-in-ram with CTKArch "live" system, I found not much to endorse using that mode. A negative of good proportion is the copy-to-ram loading time , which cannot be avoided.
Basically, faster ram is the best approach for performance enhancement in all systems.
Thus, there are herein some reasons for using flash in an arch booting system whether "live" or conventional or raid based.
My raid0 bootable system was outlined in previous post and am using it now. It is not a USB connected bus arrangement which inherently limits performance.
I find Compact Flash in UDMA or true IDE mode to provide good performance speed of 90mb/s read and 25mb/s write to be a fine alternative to hard drives. In raid0 read speed is doubled. Good reason for flash devices but not in usb mode.

USB flash storage mounted as read-only filesystem

Hello all,
I'm new to Arch Linux and trying to migrate all my works to arch. Installed KDE, GNOME3, and hardware drivers successfully But I have problems with USB flash disks. When plugging a usb device, system mounts it as a readonly filesystem. so I can't change its contents. It always happens to my flash disk, but flash disk of my friend is ok!
I tried to mount manually with super user access, but no hope. It says:
[root@myhost soroush]# mount /dev/sdb1 /mnt/
mount: warning: /mnt/ seems to be mounted read-only.

roygbiv wrote:Maybe you can post your /etc/fstab?
# /etc/fstab: static file system information
# <file system> <dir> <type> <options> <dump> <pass>
tmpfs /tmp tmpfs nodev,nosuid 0 0
/dev/sda2 / ext4 defaults 0 1
/dev/sda3 /home ext4 defaults 0 1
/dev/sda4 swap swap defaults 0 0

USB Flash Drive: Read-only filesystem

Hi
I'm trying to format a usb flash drive using various tools but they all say that it's a read-only file system. The drive is not mounted and I'm running as root. If I try to mount the drive like so with the command
sudo mount -o rw,users /dev/sdc1 /media/myflashdrive
I don't get any errors and when I go to /media/myflashdrive I can see and edit all the files (only as root however). However, any changes are not persistent. For example, if I delete any files or run
sudo rm -rf /media/myflashdrive/*
it seems to work and ls doesn't show anything, but then if a reopen the drive, the files are back.
I've tried this on other computers and even in Windows but nothing can put a scratch on it. I heard something about there being a certain bit in the first sector which can be flipped to make a drive read-only but I think it only applied to Windows.
Any advice would be greatly appreciated, but if I can't format the drive I'll probably use some thermite to toast the data on it.

Hmm. I wasn't very clear: my drive was usable originally but it stopped working while I was using Windows (I just plugged it in one day and it was read-only) and now that I use Linux I thought I'd try to fix it (I have been told that linux can do anything but I'm not so sure). I suppose it could just be a physical error on the drive but it's not got any marks or anything.
Just a thought here, if it was a physical problem, would it be possible to 'reset' it with an electromagnet or by shorting it out or would this just frazzle the chip? Maybe not the right forums for that kind of question.
Last edited by JJ.Eastwood (2011-05-26 19:50:56)

Usb stick is "READ ONLY FILESYSTEM"

hello.
i have a problem with my USB-Stick. since i gave it to a friend it does no longer work. unix says it is a "READ-ONLY FILESYSTEM". anny sugestions how i could change that?
it was not possible to reformat it by disk utility. i also tried to format it on a windows machine - didn´t work... any ideas?
best reagards
sepoe

Monkeymeetsrobot's suggestion is the first thing I would have suggested myself -- your original post made no mention of no write-lock switch -- many flash drives have them -- one of mine does and when locked would exhibit that behavior and the other one that doesn't, it still works properly.
That said, now that we know that yours doesn't have a write-lock switch, maybe you could try this:
It's a long shot, but what happens when you launch Terminal and type
ls -ld /Volumes/{usbStickName}?
If the permissions are not drwxrwxrwx, then, perhaps, from an admin-privileged account, you could
sudo chmod 777 /Volumes/{usbStickName}
and with any luck, you will have write privileges again.
Something to try....no guarantees....
Short of that, you may be giving your friend a slightly used usb flash drive as a Christmas present.
(if this solves your problem, or is actually helpful towards arriving at a solution to your problem, please consider marking this reply as "helpful" or "solved," in addition to, if applicable, marking this question as "answered")

I am connecting an external USB HDD and I can see it on my Apple Macbook Air. BUT this drive is READ only. How can I write to it?

I am connecting an external USB HDD and I can see it on my Apple Macbook Air. BUT this drive is READ only. How can I write to it?

Drive Partition and Format
1.Open Disk Utility in your Utilities folder.
2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Partition button and wait until the process has completed.
4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.
5. Set the format type to Mac OS Extended (Journaled.) Click on the Security button, check the button for Zero Data and click on OK to return to the Erase window.
6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.
Steps 4-6 are optional but should be used on a drive that has never been formatted before, if the format type is not Mac OS Extended, if the partition scheme has been changed, or if a different operating system (not OS X) has been installed on the drive.

How to attach an external USB drive read-only

I would like to hook up an external USB hard drive and would like to do so in such a manner as to ensure that absolutely nothing is modified on the drive at all. Is there some way I can specify this before I connect the drive or while I plug it in? (e.g. hold down the shift key or something like that.) I have found all sorts of posts from folks who wanted to know how to turn off read-only mode, but haven't had much luck finding out how to turn it on.
I noticed recently when I plugged in a USB stick that it sat and blinked for some time. I'm guessing that OS X was busy indexing the drive. I'm not sure if the index was written back to the USB stick, or cached somewhere locally. If it was written back to the USB stick, I would like to prevent this from happening when I plug in a real drive.
Thanks for any tips you can give me.
--wpd

If the drive is formatted NTFS, it will automatically mount read-only. If it is formatted HFS+ or FAT, I don't know of any way to external drives to mount read-only without installing OS X Server for $500.

All USB drives mount as read only for user

I have searched a bunch and thee results I find seem to be irrelevant to my situation. Most relate to a single USB media that is a problem and won't read or write.
On a new Arch install on a new computer (my third base system install). Running Gnome.
All USB mass storage devices mount as read only for the logged in user. Root has write permissions and I can mkdir no problem. It is not an issue with the USB drive itself as this occurs with multiple USB media (I've tested several SD cards on a reader and at least two drives, all the media works correctly on my existing installations)
I'm posting the contents of my /etc/group file in case there's an obvious error there I don't see, and my dmesg output upon plugging in the drive. User name is changed in the group file posted to "archie"
This is a single-user system.
/ect/group
root:x:0:root
bin:x:1:root,bin,daemon
daemon:x:2:root,bin,daemon
sys:x:3:root,bin
adm:x:4:root,daemon
tty:x:5:
disk:x:6:root
lp:x:7:daemon
mem:x:8:
kmem:x:9:
wheel:x:10:root,archie
ftp:x:11:
mail:x:12:
uucp:x:14:archie
log:x:19:root
utmp:x:20:
locate:x:21:
rfkill:x:24:
smmsp:x:25:
http:x:33:
games:x:50:
lock:x:54:
uuidd:x:68:
dbus:x:81:
network:x:90:
video:x:91:
audio:x:92:
optical:x:93:
floppy:x:94:
storage:x:95:
scanner:x:96:
power:x:98:
nobody:x:99:
users:x:100:archie
systemd-journal:x:190:
archie:x:1000:
avahi:x:84:
polkitd:x:102:
rtkit:x:133:
gdm:x:120:
brlapi:x:999:
kvm:x:78:
ntp:x:87:archie
dmesg output
[ 968.044188] usb 4-3: new high-speed USB device number 4 using ehci-pci
[ 968.170628] usb-storage 4-3:1.0: USB Mass Storage device detected
[ 968.171435] scsi7 : usb-storage 4-3:1.0
[ 969.174450] scsi 7:0:0:0: Direct-Access Generic USB SD Reader 1.00 PQ: 0 ANSI: 0
[ 969.175068] scsi 7:0:0:1: Direct-Access Generic USB MS Reader 1.03 PQ: 0 ANSI: 0
[ 969.939417] sd 7:0:0:0: [sdb] 15572992 512-byte logical blocks: (7.97 GB/7.42 GiB)
[ 969.941028] sd 7:0:0:0: [sdb] Write Protect is off
[ 969.941037] sd 7:0:0:0: [sdb] Mode Sense: 03 00 00 00
[ 969.944664] sd 7:0:0:1: [sdc] Attached SCSI removable disk
[ 969.945509] sd 7:0:0:0: [sdb] No Caching mode page found
[ 969.945517] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[ 969.952682] sd 7:0:0:0: [sdb] No Caching mode page found
[ 969.952693] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[ 969.956396] sdb: sdb1
[ 969.965003] sd 7:0:0:0: [sdb] No Caching mode page found
[ 969.965011] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[ 969.965015] sd 7:0:0:0: [sdb] Attached SCSI removable disk
I'm sure I'm just missing something in user management, but I can't find what.
Last edited by hooya (2014-04-27 03:10:49)

I am also having the same problem. Root can read and write to automounted drives, but my user cannot. I've tried with a variety of drives, I am assuming they are being automounted by root instead of the logged-in user somehow. (I am running x directly, and am not using a display manager, if that has anything to do with it).
When I look at how it is mounted it is as follows:
/dev/sdc1 on /run/media/myuser/drivename type vfat (rw,nosuid,nodev,relatime,uid=1000,gid=1000,fmask=0022,dmask=0077,codepage=437,iocharset=iso8859-1,shortname=mixed,showexec,utf8,flush,errors=remount-ro,uhelper=udisks2)

USB Stick unrecognized/read only after Gparted

Hi
I partitioned a brand new USB thumb drive with Gparted and then installed Fedora LiveOS on it. This was just a test as I really wanted to use Larch to get Arch on the stick. So I tried to repartitioned it again. But Gaparted now complains that the stick is read only and so does not change anything.
I then moved to fdisk. fdisk will allow me to look at the partitions and will even change them. But after using Fdisk to repartition and then running mkfs.whatever-i-want the partitions can not be mounted. Even dd exits with a read only drive error.
Fdisk can manipulate the partitions but it complains that DOS mode is not supported and asks me to give the c and u commands. Despite this the drive is not recognised when I plug it into the computer.
After using fdisk on the drive several times, gparted now claims that there is no valid partition table on the drive and so shows only unallocated space. But it still won't write any partition info to the device, claiming its read only!
I'm stumped! Anybody have a clue how to get around this?
emk

dd fails with an input/output error after writing 17MB. This is an 8GB stick. Fdisk shows no partitions. But is unable to write to the drive after I create partitions. Here is the output.
dd if=/dev/zero of=/dev/sdb
dd: writing to `/dev/sdb': Input/output error
32969+0 records in
32968+0 records out
16879616 bytes (17 MB) copied, 217.003 s, 77.8 kB/s
Output of dmesg when I plug in the drive
usb 4-1: new high speed USB device using ehci_hcd and address 2
Initializing USB Mass Storage driver...
scsi2 : usb-storage 4-1:1.0
usbcore: registered new interface driver usb-storage
USB Mass Storage support registered.
scsi 2:0:0:0: Direct-Access HP v115w 1100 PQ: 0 ANSI: 0 CCS
sd 2:0:0:0: Attached scsi generic sg2 type 0
sd 2:0:0:0: [sdb] 15663104 512-byte logical blocks: (8.01 GB/7.46 GiB)
sd 2:0:0:0: [sdb] Write Protect is off
sd 2:0:0:0: [sdb] Mode Sense: 43 00 00 00
sd 2:0:0:0: [sdb] Assuming drive cache: write through
sd 2:0:0:0: [sdb] Assuming drive cache: write through
sdb: sdb1
sd 2:0:0:0: [sdb] Assuming drive cache: write through
sd 2:0:0:0: [sdb] Attached SCSI removable disk
So far this looks OK. I had earlier deleted my initial 2 partitions and created one vfat partition on the drive. But then when I try to mount the drive and to repartition with fdisk dmesg gives the following:
EXT4-fs (sdb1): VFS: Can't find ext4 filesystem
EXT2-fs (sdb1): error: can't find an ext2 filesystem on dev sdb1.
FAT: bogus number of reserved sectors
VFS: Can't find a valid FAT filesystem on dev sdb1.
usb 4-1: reset high speed USB device using ehci_hcd and address 2
usb 4-1: reset high speed USB device using ehci_hcd and address 2
usb 4-1: reset high speed USB device using ehci_hcd and address 2
usb 4-1: reset high speed USB device using ehci_hcd and address 2
usb 4-1: reset high speed USB device using ehci_hcd and address 2
usb 4-1: reset high speed USB device using ehci_hcd and address 2
sd 2:0:0:0: [sdb] Unhandled sense code
sd 2:0:0:0: [sdb] Result: hostbyte=0x00 driverbyte=0x08
sd 2:0:0:0: [sdb] Sense Key : 0x7 [current]
sd 2:0:0:0: [sdb] ASC=0x27 ASCQ=0x0
sd 2:0:0:0: [sdb] CDB: cdb[0]=0x2a: 2a 00 00 00 10 70 00 00 f0 00
end_request: I/O error, dev sdb, sector 4208
Buffer I/O error on device sdb, logical block 526
lost page write due to I/O error on sdb
Buffer I/O error on device sdb, logical block 527
lost page write due to I/O error on sdb
Buffer I/O error on device sdb, logical block 528
lost page write due to I/O error on sdb
Buffer I/O error on device sdb, logical block 529
lost page write due to I/O error on sdb
Buffer I/O error on device sdb, logical block 530
lost page write due to I/O error on sdb
Buffer I/O error on device sdb, logical block 531
lost page write due to I/O error on sdb
Buffer I/O error on device sdb, logical block 532
lost page write due to I/O error on sdb
Buffer I/O error on device sdb, logical block 533
lost page write due to I/O error on sdb
Buffer I/O error on device sdb, logical block 534
lost page write due to I/O error on sdb
Buffer I/O error on device sdb, logical block 535
lost page write due to I/O error on sdb
sd 2:0:0:0: [sdb] Unhandled sense code
sd 2:0:0:0: [sdb] Result: hostbyte=0x00 driverbyte=0x08
sd 2:0:0:0: [sdb] Sense Key : 0x7 [current]
sd 2:0:0:0: [sdb] ASC=0x27 ASCQ=0x0
sd 2:0:0:0: [sdb] CDB: cdb[0]=0x2a: 2a 00 00 00 11 60 00 00 f0 00
end_request: I/O error, dev sdb, sector 4448
sd 2:0:0:0: [sdb] Write Protect is on
sd 2:0:0:0: [sdb] Mode Sense: 43 00 80 00
sd 2:0:0:0: [sdb] Assuming drive cache: write through
sd 2:0:0:0: [sdb] Unhandled sense code
sd 2:0:0:0: [sdb] Result: hostbyte=0x00 driverbyte=0x08
sd 2:0:0:0: [sdb] Sense Key : 0x7 [current]
sd 2:0:0:0: [sdb] ASC=0x27 ASCQ=0x0
sd 2:0:0:0: [sdb] CDB: cdb[0]=0x2a: 2a 00 00 00 80 c0 00 00 08 00
end_request: I/O error, dev sdb, sector 32960
sd 2:0:0:0: [sdb] Assuming drive cache: write through
sdb: unknown partition table
usb 4-1: reset high speed USB device using ehci_hcd and address 2
I don't have any ext4 partitions on it. THere should only be vfat. My initial partitions were ext3 and vfat. I then switched the ext3 to ext2 after the problems begun and finally just went with a big vfat. I initially used gparted on the drive so as to label the partitions. I really feel that gparted may be the culprit here but I have no proof. This is a brand new stick that had not been written to before.
And from gparted:
libparted : 2.3
======================
Unable to open /dev/sdb read-write (Read-only file system). /dev/sdb has been opened read-only.
Unable to open /dev/sdb read-write (Read-only file system). /dev/sdb has been opened read-only.
Unable to open /dev/sdb read-write (Read-only file system). /dev/sdb has been opened read-only.
/dev/sdb: unrecognised disk label
[1]+ Done gparted
emk
Last edited by emk (2010-07-25 00:02:50)

Read-only FAT32 USB

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