save file as read only, cross platform usb

Question

save file as read only, cross platform usb

I'm looking for a way to write video files (>4GB) onto a USB thumbs drive using my Mac that will mount correctly on Mac and Windows OS. Ideally I would like to create a Read Only USB drive.

Having looked into it i am aware that NTFS file format is probably the right way to go for cross platform compatibility. FAT 32 is not suitable as i expect the files that I need to write to the devices will be larger than 4GB.

I'm wondering if there is a way to combine the method proposed by ajduguid on Feb2, 2011 in this thread : Locking individual files onto usb to avoid deletion

with either adding support for writing to NTFS file system using the Terminal in Sierra ( https://techsviewer.com/enable-ntfs-write-mac-os-sierra/ ) or earlier version of Snow Leopard (OS 10.6.8) or using Paragon NTFS for Mac.

Writing to NTFS seems to work fine but I attempted modifying the method above to create a Read Only device but when completed my device was not recognised by either Mac or Windows OS.

Any help with this is very much appreciated.

Mike

Posted on Aug 23, 2017 3:07 AM

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Answer 1

etresoft

Level 9

56,668 points

Aug 23, 2017 3:56 AM in response to Michael Simpson1

Hello Michael,

Could you use Linux instead? Paragon is about the only Mac tool to write NTFS and I don't know if it is sufficient for what you need. There are a number of tools on Linux that can create, restore, clone, etc NTFS filesystems and images. You can combine that with dd (which is also on the Mac) to move the data to a raw usb device. It will take some work, but this is something that I know you could accomplish in Linux. It is much easier to adapt a working Linux solution than to try to attempt something on the Mac that might be impossible. You can run Linux using the free Parallels Desktop Lite available in the Mac App Store (https://itunes.apple.com/us/app/parallels-desktop-lite/id1085114709?mt=12). You might have trouble getting Parallels to access the raw USB disk. That is when you could use dd on the Mac side to handle that.

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Answer 2

Aug 23, 2017 5:20 AM in response to etresoft

Thanks again...You may have misunderstood me a little. I have not yet used Paragon NTFS for Mac, only used Terminal to allow writing to NTFS drives so not sure they would help at this stage.

I posted in developer forums I expected this would be the best place to get answers/suggestions...and you have proved me right in doing so. Thanks.

Do you have any idea whether, in theory, it is possible by modifying the method in the post mentioned above ( Re: Locking individual files onto usb to avoid deletion) to create a read only USB?

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Answer 3

VikingOSX

Level 10

123,458 points

Aug 23, 2017 3:56 AM in response to Michael Simpson1

OS X and Mac OS allow you to format that USB stick, or external drive, as exFAT, which is mutually readable by Windows and Mac, but also eliminates the 4GB individual file limitation of FAT 32. This simplifies attempting to accommodate NTFS write support via current third-party software. The exFAT filesystem is by default, the standard filesystem on SDXC cards > 32 GB.

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Answer 4

Aug 23, 2017 3:44 AM in response to etresoft

Thanks for the response.

Please excuse my ignorance...dd?

I have no understanding os Linux and would prefer to find (if it exists) a solution that is available without moving even further out of my comfort zone - I have only just started using Terminal and don't really know what i'm doing. This may be a procedure that a few of my colleagues would need to follow.

Having said that, if the solution is readily available simple using Linux I'd be interested to learn the methods involved.

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Answer 5

Aug 23, 2017 3:55 AM in response to VikingOSX

Thanks for posting...

The reason for not going down the exFAT route is because of when it became supported on the Windows side. We (the company I work for) still have a PC that does not support exFAT...I believe it was still necessary to choose to include support for exFAT in service packs for XP and VISTA. Now I know that sounds but crazy but I have to assume that a number of our clients/customers to still be using old systems such as these so want to make this as compatible as possible so that we don't become their tech support when the USB doesn't mount.

The NTFS USB I created by adding support for writing in OSX mounted and the fils were accessible on our old PC.

Does that make any sense?

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Answer 6

etresoft

Level 9

56,668 points

Aug 23, 2017 4:37 AM in response to Michael Simpson1

Hello again Michael,

You did post in the developer forum 🙂.

I suggest passing on the Linux solution. It would be far from simple.

Maybe contact Paragon directly and ask about the problem you had creating the read-only device.

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Answer 7

etresoft

Level 9

56,668 points

Aug 23, 2017 6:43 AM in response to Michael Simpson1

It is certainly possible. People do similar things on a regular basis. One such technique is "slipstreaming". Usually this involves building an image of an installer but including customized files.

If you were reformatting a disk or usb drive, all you are really doing is writing the structure of an empty file system directly into the raw storage of the device. What you are suggesting is writing the structure of an almost-empty file system directly into the raw storage of the device. If it were anything other than NTFS, it would be easy to do. Making it read-only is also another complication.

I don't know whether the hack of the built-in NTFS driver or Paragon will be able to do that on a Mac. The discussion thread you referenced is definitely the right idea. But they aren't attempting to do NTFS or a read-only version.

Do you have a budget for this task? I think it wouldn't be difficult to find a Linux programmer who could knock this out in a day or two. There are a number of web sites where people post these short-term "gig" jobs. All you need is a pure Python or other scripting language that writes a pre-formatted, read-only NTFS image and includes one or more files that are specified on the command line. Then, you can run "dd" on the command line to write the image to media. The Python script and dd would run with no problem on a Mac.

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Answer 8

Aug 24, 2017 6:12 AM in response to etresoft

Thanks again for your input.

Re budget....not my call but I would guess the MD of the company I work for won't be that interested in investing money in a bespoke solution, even though it would probably save us money in the long run with not having to re-do work when files are deleted by customers...I "could" be wrong though!

I'll give the guys at paragon a shout and see if they have any clues if it's possible with NTFS for Mac. Looks like we could do with their product either way to make things a little simpler.

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Answer 9

VikingOSX

Level 10

123,458 points

Aug 23, 2017 3:59 AM in response to Michael Simpson1

After 30 years in the computer industry, I understand about legacy support headaches.

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Answer 10

Aug 23, 2017 5:22 AM in response to VikingOSX

In your opinion and with your experience, does NTFS seem like a good route to pursue?

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