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UDF file system facts 

In 2021 we funded a fsck_udf command to recover corrupt UDF file systems, which was completed by reinoud@.

UDF's important because it's open and patent free. It's usually used on DVD/BR, but it can be used on anything else too.

It supports Unix permissions, unlike FAT. Unlike exFAT, it's patent-free for everyone, not just Windows and Linux.

Most OSes support UDF 1.02, but in NetBSD we support R/W up to version 2.60.

Consider formatting your shared drives with UDF. 😃

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UDF file system facts, part 2 

The NetBSD UDF driver is used on the PlayStation 4 and 5. Unfortunately bugs we fixed in the past have got in the way of people hacking their PlayStations. Sorry everyone. 😔

UDF file system facts 

@netbsd that’s really useful information. does UDF handle forward compatibility? Eg does a system with UDF 1.02 know how to read/write disk created with UDF 2.60?

re: UDF file system facts 

@netbsd Oh wow, I had no idea there was work done for a fsck_udf! I trialed UDF in 2018 when I wanted a performant shared data partition between Windows and Linux dual-boots (before I ditched Windows entirely). I had to drop it because eventually Windows would stop mounting it as read-write for unknown reasons. Windows chkdsk mostly removed data instead of fixing anything, and fsck from udftools was barely functional (it was not finished by any stretch, so no surprise there). I ended up going with exFAT using the Samsung Linux driver, back when it was in someone's dubious GitHub repo before it got upstreamed.

The state of most UDF implementations really is a shame. It has all the features one would need, and even has provisions for encoding Windows NT ACLs, which Microsoft never bothered to implement... When it was working in my setup, though, it was great! I/O was no issue, files from Windows ended up with reasonable default POSIX modes and nobody/nogroup as one might expect, etc...

re: UDF file system facts 

@netbsd I did later choose UDF for a USB flash drive that I wanted to populate under Linux and serve files from under NetBSD. NetBSD was (is) on a Power Mac G4 with only a small partition allocated to it on the internal HDD, and I was using it to netboot IRIX on an SGI Indy. :)

re: UDF file system facts 

@Skirmisher >The state of most UDF implementations really is a shame.

That's the point of us funding the code to make a great UDF implementation. It's all licensed under terms that should allow anyone to use it - hopefully it gets picked up, ported, and benefits the ecosystem as a whole.

This is what we do all over the place, in projects like pkgsrc too. Supporting the NetBSD Foundation supports open computing ;)

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