[TheLoneWolfling]

Or you have one filesystem that is geared towards dumb flash, and another that is geared towards smart flash.

I don't see why people try to design filesystems that do everything. As usual for hybrids, they try to do everything and as a result don't work well anywhere.

As long as you keep the limitations of dumb flash in mind (namely, that flipping bits in one direction is slow (things are a little more complex on MLC, but still doable)), it's surprisingly easy to design a filesystem that does well on "dumb" flash.

[tjoff]

This is a tangent but you seem to be under the impression that filesystems grow on trees. I've been waiting for a modern COW linux filesystem for almost a decade now. Maybe in a few years it's mature enough to wait a few more years for it to become stable? (I'm looking at you BTRFS) ;)

I guess BTRFS would fall into the filesystems that do everything category... Though at the other side of the spectrum you have filesystems that have not been tested enough or isn't maintained.

[simoncion]

FSs designed to run on dumb flash exist: https://encrypted.google.com/#q=site:lwn.net+nand+flash+file...

> I don't see why people try to design filesystems that do everything.

For general use, [0] I would rather use a FS that works on pretty much every media type [1] -and has reasonable perf- than to have to worry about whether $SPECIALTY_FS is actually tuned for $WEIRDO_BLOCK_DEVICE, or if I've failed to understand the particulars of either the FS, device, or both.

[0] That is, when getting the absolute best perf isn't a requirement.

[1] Except for like, tape, and optical RAM/WORM drives, natch.

[TheLoneWolfling]

I don't mind having a filesystem that works reasonably well on most devices. But I would consider "being able to append to a file reasonably quickly" as part of that "reasonably well".

Note that it's entirely possible to have a filesystem that's actually several different filesystems with a magic selector. (I mean, block sizes and reserved block percentages and inline inodes already are along those lines)

[simoncion]

If your underlying device is slow -as SD cards are notorious for being for any use case other than picture or video storage and retrieval-, no amount of FS juju can help you.