SD card formatting

Gary Aitken freebsd at
Mon Mar 16 18:38:07 UTC 2020

On 3/16/20 2:05 AM, Polytropon wrote:
> On Sun, 15 Mar 2020 19:06:22 -0600, Gary Aitken wrote:
>> On 3/15/20 5:00 PM, Polytropon wrote:
>>> On Sun, 15 Mar 2020 15:39:33 -0600, Gary Aitken wrote:
>>>> 11.3-RELEASE-p6 GENERIC  amd64
>>>> I'm having trouble reading SD cards formatted in my camera (Olympus
>>>> EM1-MkII) or on a Win 7 system.
>>> What filesystem is in use? For cards, it's typically FAT.
>>>> When attempting to mount, I get the following:
>>>> $ mount -t msdosfs /dev/da0s1 /mnt/memstick mount_msdosfs:
>>>> /dev/da0s1: Invalid argument $ mount -t ntfs /dev/da0s1
>>>> /mnt/memstick mount: /dev/da0s1: Operation not supported by device
>>>> Cards used without formatting *usually* seem to work.
>>> So those are preformatted (sometimes sold this way, sometimes
>>> initialized when first used in a camera).
>>>> If I look at the cards which don't mount using gpart, I see:
>>>> Card formatted in camera:
>>>> $ gpart show -p /dev/da0
>>>> =>       63 120944577    da0  MBR  (58G)
>>>>           63      32705         - free -  (16M)
>>>>        32768  120911872  da0s1  ntfs  [active]  (58G)
>>>                                  ^^^^
>>> It seems that the card has been accidentally formatted with NTFS. In
>>> most cases, cameras cannot use that. If you want to mount it on
>>> FreeBSD, use ntfs-3g.
>> As stated above, this is a card formatted _in the camera_.  So the
>> camera can read it fine.  The problem is fbsd can't mount it.
>>From the program output presented, it seems that you're
> trying to mount a NTFS partition using the FAT mount option,
> which will not work. Try ntfs-3g (needs to be installed;
> mount_ntfs is no longer part of the OS).

Ah, that's a help, thanks.

# ntfs-3g /dev/da0s1 /mnt/memstick
NTFS signature is missing.
# ntfs-3g.probe --readonly /dev/da0s1
NTFS signature is missing.
# file -r - </dev/da0
/dev/stdin: DOS/MBR boot sector; partition 1 : ID=0x7, active, start-CHS (0x2,10,9), end-CHS (0x3ff,254,63), startsector 32768, 124702720 sectors
# file -r - < /dev/da0s1
/dev/stdin: DOS/MBR boot sector

>>> Personally, I tend to leave the formatting to the camera which I want
>>> to use the card in; the camera "knows best" what it can uderstand.
>>> :-)
>> In this case, the camera is not the problem; cards formatted in the camera
>> are usable by the camera.  But they aren't mountable on fbsd.  So I can't
>> transfer the files to fbsd, either from the camera or by inserting the
>> card in an fbsd usb adapter.
> Depending on the camera, a USB connection can show up as
> a mass storage device (leads to /dev/da<something>) or a
> MTP interface (leads to /dev/ugen<something>). In many cases,
> the "personality" can be seleted by the menu in the camera.

It shows up as mass storage, /dev/da0 in this case

>> Since cards formatted by the camera are not mountable on fbsd, I was
>> hoping to find a way to format the card on fbsd that would be
>> readable both by the camera and by fbsd.
> The camera seems to prefer NTFS, so when you (correctly)
> format a card as FAT, the camera refuses to read it. However,
> that's the first occassion I hear about a camera that seems
> to use NTFS natively... not that this is impossible, it's
> just something I never heared about it. :-)
>>> There is a simple reason: Several variants of FAT exist, and some
>>> cameras often only support one out of that bag. If you guess (and
>>> use) the wrong one, the camera will report an error. So, as I
>>> suggested, let the camera do the right thing.
>>>> If I again format the card in the camera, I can't mount it.
>>> Have you checked _how_ the camera formats it? Check with gpart (or
>>> fdisk, it still works!). There's also the following totally unelegant
>>> way:
>>> # file -r - < /dev/da0
>>> and / or
>>> # file -r - < /dev/da0s1
>>> You should see a FAT summary.
>> For a card formatted in the camera, which the camera can read but fbsd
>> cannot mount:
>> # file -r - < /dev/da0
>> /dev/stdin: DOS/MBR boot sector; partition 1 : ID=0x7, active,
>> start-CHS (0x2,10,9), end-CHS (0x3ff,254,63), startsector 32768,
>> 120911872 sectors
>> # file -r - < /dev/da0s1
>> /dev/stdin: DOS/MBR boot sector
>> # mount_msdosfs /dev/da0s1 /mnt/memstick
>> mount_msdosfs: /dev/da0s1: Invalid argument
> According to the gpart output, it's not FAT (msdosfs),
> but NTFS.
>> For a card never reformatted (i.e. formatted by the manufacturer, and
>> used in the camera); this card is usable by the camera and mountable
>> by fbsd:
>> # file -r - < /dev/da0
>> /dev/stdin: DOS/MBR boot sector; partition 1 : ID=0xc, active,
>> start-CHS (0x0,130,3), end-CHS (0x3ff,254,63), startsector 8192,
>> 31496192 sectors
>> # file -r - < /dev/da0s1
>> /dev/stdin: , code offset 0x0+3, OEM-ID "        ", sectors/cluster 64,
>> reserved sectors 504, Media descriptor 0xf8, sectors/track 63,
>> heads 255, hidden sectors 8192, sectors 31496192 (volumes > 32 MB),
>> FAT (32 bit), sectors/FAT 3844, serial number 0x0, unlabeled
>> # mount_msdosfs /dev/da0s1 /mnt/memstick
>> # ls /mnt/memstick
>> DCIM                            System Volume Information
> This doesn't actually look like a "mint condition" card. A
> directory named "DCIM" is typically created by a camera.
> However, _this_ card is FAT-formatted, and therefore can be
> mounted with msdosfs as correctly shown above. The directory
> name "System Volume Information" suggests it has been in a
> "Windows" PC before. COnclusion: Card works both in camera
> an in "Windows" PC.

Correct, it's not an unused card.  It's been put in the camera,
recorded on, and then put in a windows system to transfer images.

> So the camera seems (!) to initialize cards as NTFS (strange,
> but surely possible), but also understands FAT.

That seems to be the case.
Since ntfs-3g doesn't seem to like the camera-generated NTFS
filesystem, it seems my best option is to try to format with
the FAT it understands.

> All you need to do now is to replicate _that_ formatting.
> The output shows "FAT (32 bit)", and the partitioning also
> looks reasonable. You should be able to create this either
> with gpart + newfs_msdosfs (should be quite standard today),
> or the traditional way with fdisk + newfs_msdosfs (archaic,
> but should also still work).

Tried the following:

# gpart create -s MBR /dev/da0
da0 created
# gpart show -l da0
=>       63  120944577  da0  MBR  (58G)
          63  120944577       - free -  (58G)
# gpart add -t fat32 -a 4K /dev/da0
da0s1 added
# gpart show -l /dev/da0
=>       63  120944577  da0  MBR  (58G)
          63          1       - free -  (512B)
          64  120944576    1  (null)  (58G)
# newfs_msdos -F 32 -A /dev/da0s1
/dev/da0s1: 120885440 sectors in 1888835 FAT32 clusters (32768 bytes/cluster)
BytesPerSec=512 SecPerClust=64 ResSectors=46 FATs=2 Media=0xf0 SecPerTrack=63 Heads=255 HiddenSecs=0 HugeSectors=120944576 FATsecs=14761 RootCluster=2 FSInfo=1 Backup=2
# mount -t msdosfs /dev/da0s1 /mnt/memstick
mount_msdosfs: /dev/da0s1: Invalid argument

Obviously I'm missing something?

>>>> I need to reformat these cards so I can use them in the camera and
>>>> on freebsd, and apparently neither the camera nor win7 does that,
>>>> so... What's the right way to lay out, format, and create a file
>>>> system on an SD card so it is usable by cameras and windoze?
>>> Typically using the _camera_ to do this job is the right thing. It's
>>> often nice to have the card in "mint condition" (i. e., nothing on
>>> it, no partitions, no filesystems). Using dd to overwrite the first
>>> MB should be enough. On a "Windows" PC, the card should then
>>> correctly be recognized as FAT. And on FreeBSD, you can easily mount
>>> it with the -t msdos type. Just make sure that you use /dev/da0 or
>>> /dev/da0s1 (some cameras are tricky and initialize the card as
>>> /dev/da0 instead of /dev/da0s1, I never understood why).
>> The problem is, on fbsd I _can't_ mount it.
>> # dd if=/dev/zero of=/dev/da0 bs=1K count=1K
>> 1024+0 records in
>> 1024+0 records out
>> 1048576 bytes transferred in 0.507045 secs (2068012 bytes/sec)
>> put card in camera and format it
>> # gpart show -r /dev/da0
>> =>       63  120944577  da0  MBR  (58G)
>>            63      32705       - free -  (16M)
>>         32768  120911872    1  7  [active]  (58G)
>> # mount -t msdosfs /dev/da0s1 /mnt/memstick
>> mount_msdosfs: /dev/da0s1: Invalid argument
>> The card is readable by windows, however.
> It would be nice to see if _this_ card now is FAT or NTFS.
> If it's NTFS, "Windows" will of course be able to use it.
> On FreeBSD; you need to use nrfs_3g to mount it, though. :-)

As shown earlier, ntfs-3g won't mount it, even though it's type 7 (ntfs)

Thanks for your perseverance on helping explain all this...


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