ext2 on sd

Attempted to format my microSD card as ext2 instead of the default fat32. No dice. My main motivation was to facilitate backups with rsync since fat32 is generally incapable of doing incremental backups with Linux. But Android just doesn't play nicely with nonstandard SD setups.

Unfortunately I was unable to find any good documentation regarding the SD mounting process. My phone uses a Vold fstab with a dev_mount command (?). And Sapphire definitely includes an ext2 kernel module, but I couldn't even mount the ext2 partition manually. Modprobe indicated that ext2.ko loaded fine, but still did not mount.

Apparently Android mounts the first fat32 partition it finds as /sdcard. And as far as I can tell, this is not really a user option. Curious design decision that I would like to learn more about... Everything on the web seems related to apps2sd, which requires a separate ext2 partition in addition to the fat32 data partition. I just wanted all my music, settings, etc. on an ext2 data partition. No need for apps2sd.

Perhaps I will look into this later. But right now it looks like it's not worth the effort.

In a related note, Android exposes the entire fat32 partition when USB Storage is enabled. I suspected there might be other partitions for Android data that were hidden from the user. But the default partitioning setup is simply one fat32 partition.