

Android 2.3 to use ext4 - dmaz
http://android-developers.blogspot.com/2010/12/saving-data-safely.html

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angusgr
I'm confused. A few years ago, the perceived wisdom was that dedicated flash
filesystems like yaffs2/jffs are better (performance & longevity-wise) for
running on flash devices than more general block filesystems like ext4/3/2.

What am I missing here? Are flash controllers, or the mtdblock kernel layer,
now smarter than they were previously?

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cnvogel
The dedicated flash filesystems are designed to run directly (or separated by
only a very thin layer of abstraction, e.g. the mtdblock you mentioned) on
flash chips, so they take care of wear-leveling and use flash-friendly data
structures.

Most modern phones these days run off sd-cards that take care of all these
issues, and it looks like the algorithms embedded in these small cards,
combined with normal off-the-shelf filesystems deliver better performance and
better reliability than what the special-purpose filesystems could.

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nuclear_eclipse
Although how does this explain the Nexus S, which is using an embedded 16G
flash chip instead of an SD card? Are there equivalent wear-leveling
algorithms included with modern flash controllers?

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cnvogel
I don't know specifically for the Nexus S, but as a manufacturer you can buy
flash-chips that have a mmc interface, so that they look like an SD-card to
the microprocessor but can be soldered like a "usual" chip.

E.g. look for SanDisk iNAND.

------
akent
"There are several layers of buffering between you and the hardware!"

I hope this does not come as a surprise to anyone.

~~~
angusgr
Nevertheless, there were a lot of dramas when ext4 first came across to the
mainstream Linux distros (as per the extra reading links in the blog post.)

So I can see why Google want to make it perfectly clear that this is
happening.

