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ABS: The guts of Android: ext4 vs yaffs2

Posted Apr 29, 2011 16:27 UTC (Fri) by csimmonds (subscriber, #3130)
In reply to: ABS: The guts of Android by karim
Parent article: ABS: The guts of Android

I think the choice of file system is dependent on the storage technology: Android devices with raw NAND flash will continue to use yaffs2, I imagine, but those using eMMC, which is basically a micro SD card soldered on to the main board, have to use a "normal" file system. In that case, ext4 seems a reasonable choice. Coincidentally, ext4 is likely to be more multi-threaded than yaffs2. So, I don't think it is a straight yaffs2 vs ext4 debate, it is more a question of horses for courses.

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Posted Apr 29, 2011 16:48 UTC (Fri) by karim (subscriber, #114) [Link]

Agreed. I've never thought about this as an ext4 vs. yaffs2 thing. But I am wondering if the shift to emmc is due to multi-core (as one would conclude if Ted's line of thought is followed) or due to the fact that hardware manufacturers just wanted their customers to be able to use standard filesystems on their devices (or the customers asking for it.) In all likeliness, the decision was made by hardware design guys ...

nand to eMMC - pin counts

Posted Apr 29, 2011 22:01 UTC (Fri) by pflugstad (subscriber, #224) [Link]

I believe it's about pin counts. Bare nand requires a lot of pins. eMMC is essentially a serial interface, with variable width data path (8 bit max). So by going with eMMC, you reduce your required pin counts, which equals cheaper boards.