Comment by mikece | Hacker News Reader

Comment by mikece | Hacker News Reader

> Why not exFAT... Microsoft owns several patents, and anyone who implements or uses exFAT technology needs Microsoft's permission, which typically also includes paying fees to Microsoft.

While BigFAT not being encumbered by any patents is a good thing, the camera industry have pretty much standardized on exFAT for their removable file storage format. Something I'm curious about is how a 5GB video file (quite common and actually on the smaller size for 4K and 8K recording sessions) is written and accessed between the two file systems. BigFAT says that the file would be written in 4GB chunks; is there something similar happening with exFAT or is the file "one chunk?" (Apologies if I have the terms wrong -- I'm not a filesystem expert.) The author laments that the exFAT format has been adopted for SDXC cards but given who all is in this group and what their use cases are I can discount "because Microsoft strong-armed them" as a reason for them selecting it.

The industry could have used UDF. Derived from ISO 9660, but it supports read-write random access storage.

I'm guessing they didn't if FAT12/16/32->exFAT driver changes are comparatively simple, and/or results in a smaller code base to support FAT32 and exFAT on the same device (e.g. a camera).

And on a camera that costs anywhere from USD$1000 to USD$6500 does the cost of an exFAT license really matter?

Yes, it does.

If you manufacture 100K of them, and save 10 dollars on every piece, you got an extra million in savings.

From the wiki, my understanding is the licence is $0.25 a unit, not $10?

It was a number to illustrate a point, not exact figure for this specific case.

Yes, the manufacturers will go great lengths to minimize variable costs. If they can shave $0.25, they will. At volumes, it matters.

ExFAT is not limited to a 4GB maximum file size. It just has more than 4GB in the file.

I guess 4GB seemed like a reasonable limit when FAT32 was designed.

Most likely FAT32 has a 32bit number for file size and ExFAT presumably has either a 64bit one or stores file size in some format other than bytes.

> I guess 4GB seemed like a reasonable limit when FAT32 was designed.

FAT32 was always seen as stop-gap measure for low-end consumer hardware when introduced in 1996; NTFS was introduced 3 years prior to handle terabyte-scale data for enterprise users.

> Most likely FAT32 has a 32bit number for file size and ExFAT presumably has either a 64bit one

Correct.

I actually am disappointed that Microsoft has a chance to fix some inherent problems with FAT but didn't, even considering the main use case of a simple FS. Notably, it still has the notorious year 2100 bug (or 2108 bug, depending on the implementation), the metadata is weird and not at all straightforward, it's basically just extending FAT32 and some minor updates since Unicode and UTC are now here.

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