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MitsuhaMiyamizu / raspberrypi-openwrt

Automatically exported from code.google.com/p/raspberrypi-openwrt
GNU General Public License v2.0
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EXT4 filesystem on an SD is a bad idea #2

Open GoogleCodeExporter opened 9 years ago

GoogleCodeExporter commented 9 years ago 
I would propose using ramdisk + jffs2 overlay on SD storage media. This will 
minimize number of writes to the media so it will last longer. Also read speeds 
will be much faster.

If you think rpi memory is too valuable, you can just use yaffs, jffs2 or any 
other file system that was specifically designed to be used with NAND flash (no 
seeks, must write to random blocks, no data alignment, etc).

Original issue reported on code.google.com by va...@grinco.eu on 20 Aug 2012 at 10:37

GoogleCodeExporter commented 9 years ago 
Have a look here http://lwn.net/Articles/502472/ concerning Ext4 on SD storage.

SD card media is not the same as raw Flash and provides a block based interface 
to the host. Some SD cards even have their own wear leveling integrated and 
might even interfere with the chosen file system.

I agree, that write access should be minimized. Even better would be a 
read-only root file system combined with a separate writable area (overlay), 
for configuration data. But this can be very application specific.

So, it is not really a defect, but more a feature that should be added in the 
future.

Original comment by nathan.h...@gmail.com on 22 Aug 2012 at 1:04

GoogleCodeExporter commented 9 years ago 
Just turn off journal on EXT4 with tune2fs and it should be fine. People used 
to use ext2 before which was fine but not ext4 with journal turned off should 
handle it well.
Agree that a read-only filesystem with writable area just for things like 
configuration is the ideal.

Original comment by fhfredi...@gmail.com on 29 May 2013 at 1:07