(cache)USB stick refuses to leave read-only mode. How to make it writable again?

exerceo · 10-05-2025, 02:46 PM

dmesg:

Code:

[2304237.356095] scsi 5:0:0:0: Direct-Access      USB      SanDisk 3.2Gen1 1.00 PQ: 0 ANSI: 6
[2304237.356396] sd 5:0:0:0: Attached scsi generic sg4 type 0
[2304237.356778] sd 5:0:0:0: [sdd] 60063744 512-byte logical blocks: (30.8 GB/28.6 GiB)
[2304237.359283] sd 5:0:0:0: [sdd] Write Protect is on
[2304237.359287] sd 5:0:0:0: [sdd] Mode Sense: 43 00 80 00
[2304237.359617] sd 5:0:0:0: [sdd] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA

hdparm:

Code:

# hdparm -r0 /dev/sdd

/dev/sdd:
 setting readonly to 0 (off)
 readonly      =  1 (on)

It's a SanDisk Ultra USB stick. It's fully readable and no data is corrupted.

It is also write-protected on a different computer, so the issue is with the USB stick.

If there is no way to get it writing again, it's not that big of a loss, but it would be nice to have it working again.

sgosnell · 10-05-2025, 03:16 PM

I'm not familiar with that model. Dmesg says write protect is on. Is there a physical switch on the device? SD cards have a write-protect switch, but I don't know about that device. If there is no switch, the drive is possibly failing. Becoming read-only is a classic failure mode for flash drives.

teckk · 10-05-2025, 03:44 PM

How about this:
https://askubuntu.com/questions/1016...protection-off

JJJCR · 10-05-2025, 08:33 PM

Quote:

Originally Posted by exerceo

dmesg:

Code:

[2304237.356095] scsi 5:0:0:0: Direct-Access      USB      SanDisk 3.2Gen1 1.00 PQ: 0 ANSI: 6
[2304237.356396] sd 5:0:0:0: Attached scsi generic sg4 type 0
[2304237.356778] sd 5:0:0:0: [sdd] 60063744 512-byte logical blocks: (30.8 GB/28.6 GiB)
[2304237.359283] sd 5:0:0:0: [sdd] Write Protect is on
[2304237.359287] sd 5:0:0:0: [sdd] Mode Sense: 43 00 80 00
[2304237.359617] sd 5:0:0:0: [sdd] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA

hdparm:

Code:

# hdparm -r0 /dev/sdd

/dev/sdd:
 setting readonly to 0 (off)
 readonly      =  1 (on)

It's a SanDisk Ultra USB stick. It's fully readable and no data is corrupted.

It is also write-protected on a different computer, so the issue is with the USB stick.

If there is no way to get it writing again, it's not that big of a loss, but it would be nice to have it working again.

some usb stick, got a slide switch to make the USB read only. I am not sure whether that USB stick got one, check on it.

or try:
sudo mount -o remount,rw /dev/sdd /mnt/usbpoint

colorpurple21859 · 10-06-2025, 10:00 AM

Is the partition table something other than msdos or gpt?

DavidMcCann · 10-06-2025, 11:02 AM

Linux makes usb sticks read-only when the filing system seems to be corrupt to prevent you making it even worse.

The first step is to use fsck to see if it will clean up the device. If that works, you are probably OK.

If fsck doesn't work, or if the device gives trouble again in the future, you need to save the contents and reformat it. Gparted should work, but if it won't, you may still be able to rescue the thing. Unmount, after noting its /dev name, and run this command after which gparted should work.

Code:

dd if=/dev/zero bs=1M count=10 of=/dev/whatever

If you have further trouble, then the only solution is replacement

exerceo · 10-09-2025, 04:51 PM

Quote:

Originally Posted by JJJCR

some usb stick, got a slide switch to make the USB read only. I am not sure whether that USB stick got one, check on it.

A physical switch?

Quote:

or try:
sudo mount -o remount,rw /dev/sdd /mnt/usbpoint

Doesn't work. It seems to be on a hardware level.

Quote:

Originally Posted by DavidMcCann

If you have further trouble, then the only solution is replacement

I did some research and my closest guess would be that firmware of the USB stick refuses to write any more because it reached its end of life, as suggested by this post by AnthonyNYC from the now defunct CNET forum.

I used it as for a portable Linux installation for some time, so it might have been exposed to workloads it wasn't designed for. But it still reads at solid 140 MB/s, which is close to its advertised speed of 150 MB/s. And it never had corrupted data. But it shouldn't anyway, because that's expected from a reputable brand. Maybe SanDisks's firmware is "over-cautious" and pre-emptively write-protected it.

JJJCR · Yesterday, 12:29 AM

From this link: https://darwinsdata.com/what-happens...s-write-limit/

It says:
However, an SSD past its write endurance may still be readable for months or years in a read-only state.

Maybe true for older ssd's, for newer ssd's I believe this is not applicable anymore.

pan64 · Yesterday, 02:47 AM

Quote:

Originally Posted by exerceo

Doesn't work. It seems to be on a hardware level.

Yes, probably a real switch. Or a corrupted filesystem. Or a damaged device. Or a damaged usb port.

TenTenths · Yesterday, 05:31 AM

Sandisk will go read-only at the USB controller firmware level if it detects too many errors. Back stuff up and throw it in the bin or shred it.

onebuck · Yesterday, 06:30 AM

Hi,

No " SanDisk Ultra USB stick" have a physical protect switch.

TenTenths · Yesterday, 07:01 AM

Quote:

Originally Posted by onebuck

Hi,

No " SanDisk Ultra USB stick" have a physical protect switch.

Yes, while they may have a physical protect switch, they ALSO have firmware that makes the drive read-only when errors are detected.

I'm not pulling this info out my butt, but from the research I previously did when I had a similar problem.

onebuck · Yesterday, 07:34 AM

Hi,
You can check the Sandisk site to find none have a write protect physical switch but yes there are the means to switch via firmware.

EDIT: Some older SD/microSD cards do have a physical switch but no USB. As stated before if USB Sandisk is showing protected then it is software related.

TenTenths · Yesterday, 08:19 AM

Quote:

Originally Posted by onebuck

Hi,
You can check the Sandisk site to find none have a write protect physical switch

I'm positive I had one "back in the day", although that could be obscured by the mists of time! Or maybe it was a thing then

onebuck · Yesterday, 09:20 AM

Hi,

Quote:

Originally Posted by TenTenths

I'm positive I had one "back in the day", although that could be obscured by the mists of time! Or maybe it was a thing then

A lot of off brand sometimes do have a write protect switch. But as I said before that some older SD/microSD cards do have a physical switch which is a standard but no consumer Sandisk USB Flash. As stated before if USB Sandisk is showing protected then it is software /firmware related via the controller or the system.

As one should consider a write protect switch is a potential failure point. Firmware/software level write protect is flexible plus a secure means to protect.
Hope this helps!