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Linux RT File System support for removable SD Card - ARM/Linux/Zynq/sbRIO-9651

Hi team,

Scot requested me to post it for disscusstion and support about my question.

Here is the question from our customer.

I would like to make it to be simple question.

Customer has an experience that he used the exFAT format(128G) with cRIO platform(Linux such as NI 9034) by several setting on Linux UI.

As we know, FAT32 format has a limitation up to 32G.

How could customer use exFAT format or another format with SOM(9651) to extend SD card memory over 32G?

Thanks in advance

Sesun

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Hi Sesun,

As it stands, it seems that exFAT is in the same position as NTFS regarding support on Linux: there's limited support natively (as provided by the kernel) but there's better support through the FUSE (Filesystem in USErspace) project. While this is certainly possible to enable, it's going to require some work and, if you're not using the 2016 OS on the cotnroller, rebuilding the kernel to support FUSE.

FAT32, as a filesystem, does not have a 32 GiB limitation (FAT32 supports volume sizes up to 127 GiB), you can certainly format an SD card or a USB removable drive that is larger than 32 GiB as a FAT32 filesystem. This is a limitation that Microsoft put in place (arguably justafiable since FAT32 is less-than-reliable, and with more storage you run greater risks of corrupting the underlying filesystem).

As it stands, there are a couple of options:

  1. Format storage using something other than Microsoft Window (XP and onward)
    • + Simple from the effort standpoint
    • - Only works on devices up to 127 GiB
    • - FAT32 is prone to corruption on data loss with unexpected power-loss/removal
    • - Requires software installed to Windows to support formatting the device
  2. Format with EXT3
    • + Well-tested robust journaling filesystem (resistent to corruption and dataloss due to power loss or removal)
    • +  Support devices up to 4TiB
    • - Requires software installation on Windows (e.g. http://www.ext2fsd.com/)
    • - Uncertainty on the robustness of that software required for Windows
  3. Format with exFAT
    • + Least effort/modification of Windows systems
    • - Requires significant effort and work on the NI Linux RT side
    • - Uncertainty on the robustness of the exFAT/FUSE software on NI Linux RT
    • - Installing additional software through MAX may lose the changes required to use exFAT

NOTE

Of course, using a native Linux filesystem on the SD card and accessing the storage from a Windows machine using a Windows Share (configured through SAMBA) could also be a solution, depending on the requirements from the customer.

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Can we get more information from the customer on the steps he used to get this working on the 9034 via the UI? If he has a setup that it is working on cRIO-9034 (i.e. 64bit x86, NI Linux-RT) we should be able to replicate the configuration on the SOM-9051 (32bit ARM, NI Linux-RT)*

* although it could involve some re-building

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Hi,

Thanks for your support!

Customer, our alliance partner, could access the sd card with FAT32 format on this morning.

If he needs more information or support, he would leave the reply on this post.

Best regards

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