What I'd like to know is why my 2023 phone is still every bit as flaky as my 2018 phone was. For a while I was blaming my Linux solution but every time I try to use it on Windows it's just as flaky.
Fundamentally, accessing files on a live filesystem is a solved problem, and has been since before smart phones. I don't even know how they made such a broken setup.
(I believe the problem with USB mass storage is that it's closer to an IDE/SCSI protocol than a filesystem protocol. You can't have one bit of the system running around "accessing files" while you've got something else "moving the simulated drive head and writing this sector". In principle you could put the work in to make it all work out, but then it would be as flaky as the media access is now, only for a good reason rather than laziness/lockin.)
The situation with USB is a lot more complicated than it appears. See things like this for instance: https://unix.stackexchange.com/questions/120368/make-a-compu... The controllers that sit between the port and the computer can create significant limitations versus what is theoretically possible if you were directly bit-banging the cords.
You can do this with an ethernet cable, if you have one and an ethernet port on both ends. You can manually set up a network on just that cable and transfer at full speed. (AFAIK all modern ethernet ports are capable of figuring out that they need to crossover in this situation and you haven't needed a special crossover cable in a long time.)
If the sd card is mounted by your computer, you can't run any apps on the phone that need to use the sd card. That means, apps you moved to the SD card for space reasons, or apps that might save photos to the SD card (such as messengers).
If your computer messes up the filesystem, then you're in a world of hurt.
If multiple apps can access the filesystem at the same time, why couldn't also some app (background system process) read from / write to the filesystem in an android multi access compatible way, while serving the mass storage device API on the other side
That's possible, but really challenging to do because mass storage is block oriented, the host (desktop) is likely to do read and write caching, and there's no mechanism for a host to say I finished writing this file, and there's no mechanism for a device (phone) to say blocks changed from under you.
The paradigm for block oriented filesystem access is exclusive access, and filesystem code is built around that. There's some niche filesystems around multiple simultaneous access to block devices, but I don't know if there's any that are open source; mostly people don't setup scsi/sas/das disk arrays with two hosts anymore, and when they do, they're much more likely to have exclusive access with failover than simultaneous access.
If you had a team of really detail oriented developers capable of getting this done for Android and desktop platforms, wouldn't you rather they work on something else?
Another approach might be to build a virtual filesystem to export as a block device on usb connection that's essentially a snapshot of the current one, and then you sync any changes that were written on usb disconnect, but then you need to manage divergent changes and that's unfun too.
SMB over USB would be terrible in many ways, but probably handle this use case much better.
> If you had a team of really detail oriented developers capable of getting this done for Android and desktop platforms, wouldn't you rather they work on something else?
If you can improve the world (mass storage device is really wide spread) this way, why not?
For better or worse, most people's photos never get transferred to a computer. Heck, there's a ton of people who don't have a non-phone computing device. Pushing their photos to the cloud so they see them after their current device dies is better than working on a new filesystem that allows for multiple host simultaneous access and porting that to everything. I could make a huge list of more tractable things that this hypothetical team could work on to make Android better for way more people.
Top on my list would be getting it so the touch screen just works every time. I can't count the number of times I've had to turn the screen off and on, because the touch screen came up in a way that I can't swipe up to get the code entry because swiping from the bottom to the top of the screen doesn't move it enough. I've had this happen on pretty much all my androids.
Things like booting faster would actually be nice. Especially since sometimes phones reboot in pockets. Setting up applications for faster starting would be amazing. It's not all in Google's court, but a basic hello world with the Android IDE starts up rather slow, even if you've noticed you need to compile a release build.
