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I am having a version strange problem with a 4GB ATP Industrial Grade Compact Flash Card. I am trying to use it as the boot storage for a ALIX single board PC.

When I insert it into another Linux machine I see:

[  421.320908] scsi 3:0:0:0: Direct-Access     eUSB     Compact Flash    5.06 PQ: 0 ANSI: 2
[  421.331377] sd 3:0:0:0: Attached scsi generic sg2 type 0
[  422.670588] sd 3:0:0:0: [sdb] 7847280 512-byte logical blocks: (4.01 GB/3.74 GiB)
[  422.700420] sd 3:0:0:0: [sdb] Write Protect is on
[  422.700424] sd 3:0:0:0: [sdb] Mode Sense: 00 77 bd 6f

Then when I try any kind of write operation with it, I get:

dd: failed to open ‘/dev/sdb’: Read-only file system

Things I have tried so far:

  • There doesn't appear to be any kind of physical write-protect switch on it
  • I am able reformat it, write files, read them back on a Mac
  • I have successfully zeroed the whole card on my Mac (dd if=/dev/zero of=/dev/disk1 bs=10m)
  • I have tried using hdparm to disable read-only mode (hdparm -r0 /dev/sdb), which doesn't error but doesn't disable write-protect either.
  • I don't have any of these problems with other compact flash cards - but I want to use this one because it is much larger - and should be better because it is industrial grade.

On my main Linux machine, I am using Debian 8 (Jessie) with Linux kernel version 3.16.0-7-amd64.

It feels like there is some kind of soft write-protect lock applied to the compact flash, that only Linux seems to understand.

Does anyone have any other ideas of what to try, or what might be wrong?

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  • 1
    What file system are you using on it? Have you tried unmounting/re-mounting as root? Commented Jan 18, 2019 at 11:20
  • I put a FAT32 file system on it using my Mac. I am able to mount/unmount that read-only. But the problem seems to be lower-level than the filesystem or even the partition table. Commented Jan 18, 2019 at 11:33
  • Ok. Have you tried other filesystems? What happens if you format it on mac, then try to set up a filesystem on it in Linux? Commented Jan 18, 2019 at 11:35
  • If I try and re-partition it on Linux I get: cfdisk /dev/sdb cfdisk: cannot open /dev/sdb: Read-only file system Commented Jan 18, 2019 at 12:31
  • 2
    maybe you can fix this with the quirks mode of the usb_storage driver for this specific device, see askubuntu.com/a/1088434 Commented Jan 18, 2019 at 12:32

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Maybe you can fix this with the quirks mode of the usb_storage driver for this specific device, see https://askubuntu.com/a/1088434

If you have to use the quirks mode this probably means that the Compact Flash card's behavior differs from (most) other CF cards.

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