On Monday 31 December 2012, Phillip Norisez wrote:
Hello.
Are you the Arnd Bergmann that published the article "Optimizing Linux with cheap flash drives" in lwm.net on February 18, 2011? If so, I would greatly appreciate it if you could answer a question.
Yes, that is me.
My name is Phillip Norisez and I am in the process of putting together an embedded Linux on a custom-designed board using a TI ARM DM3055 microprocessor. My question is, is there any updated information about using SD cards as Linux boot devices, especially as regards both the incompatibilities your article raises and lifetime expectations?
This latter is due to the fact that the board will be used as part of a device which must be usable indefinitely in a third-world environment, without access to high-tech facilities, but must last longer than the typical cell phone.
There are two important recommendations I have:
* The Samsung 32GB Class 10 MB-SSBGA and MB-MSBGA cards are apparently based on an eMMC controller that has much better characteristics when using a nonstandard file system on them. This does not apply to the smaller cards or to any other brands I have seen, and of course it may change in the future. I have not yet tested Samsungs new UHS-1 compatible version of those cards.
* The new f2fs file system has been merged into the linux kernel for version 3.8. This should have a *much* better long term reliability for normal cards than any of the existing file systems we have in Linux. It is fairly new, so I would not consider it as stable as the other file systems, but on unreliable SD cards, the end result is probably better, especially if the product you want to ship is going to upgrade to a future kernel version that fixes the bugs that are yet to be found.
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Arnd