On Fri, May 06, 2011 at 11:13:39AM -0700, Charles Krinke wrote:
The next issue is the flash file system. Normally, I like to use JFFS2 for reliability as embedded devices frequently have their power switch turned off at any time. I do understand that UBIFS is getting more prevalent lately and I wonder if you or anyone else has a comment on the suitability of UBIFS in an environment where the power will be turned off and on exexpectdly and frequently.
In googling UBIFS problems, I do see posts across the internet of UBIFS devices that will not boot after power is turned off and on. My experience with JFFS2 is that it has always recovered during boot with all the designs I have participated in over the last several years. Admiteddly, the act of doing something like "scandisk" on boot slows the boot down, but does seem to add reliability.
It has been very resilient to power failures in my experience -- the Linux ubifs code has always managed to recover, and very quickly.
The main pitfall is that U-Boot's support for ubifs is only the read-only subset of Linux's. That means it can read from a consistent ubifs partition, but not from one that needs repair (because that requires writing). So you can't rely on booting your Linux kernel *from a ubifs partition*. But if you have your kernel in a separate, read-only uImage partition you should be fine (it's just more annoying to update kernels).