Yaffs Better Than Cramfs

[Kitsu]

I was just reading an article somewhere on NAND vs. NOR flash and I ran across this:
YAFFS - Yet Another Flash File System - A filesystem designed for NAND flash memory.
Project page

I just wanted to point it out. Of course a RO filesystem will give the best life for your NAND, but if you wanted to actually use it, or you are a developer, it would be nice to have an error-resistant file system to work with. Looks like bootstrapping might be a problem though?

 

[theoddbot]

yaffs and jffs2 are very similar in the way they work. jffs2 was originally for NOR flash devices but has now been ported to NAND. I don't think yaffs is being worked on any more.

Because the filesystems are totally unstructured, the whole partition has to be scanned at mount time to replay the logs, reconstructing the state of the filesystem. So I would expect boot times to be similar to jffs2.

Bootstrapping would be a matter of formatting your extended nand area to yaffs and installing a custom kernel, exactly the same as installing my cramfs setup.

Also, the next release will probably use squashfs (better compression) with a custom translation layer.

I've further partitioned the NAND layout, to give 2 extra 16mb partitions to play with, so there's no reason why you couldn't have a separate read/write filesystem on one of these other partitions for storing data or messing around.

 

[judge0]

@theoddbot: Just got back from vacation, and so much changes. GREAT work on the custom bootloader.

The original poster was close, but as you mentioned YAFFS is not under development anymore. On the other hand YAFFS2 is. Page is HERE, amongst other pages.

It is also journalled, with the option to turn journal off and just record results of block error testing to a log file.

Now to try out your new bootloader, any idea of how much time it will take?

 

[Kitsu]

Yeah, having several partitions sounds like the best option. That way you would have control over how much of your NAND gets flashed to death.

BTW, I just got another SD card and if I can flash with this one I'm looking forward to trying out your next firmware!