On Sun 2009-01-04 17:06:34, Theodore Tso wrote: > On Sun, Jan 04, 2009 at 01:49:49PM -0600, Rob Landley wrote: > > > > Want to document the granularity issues with flash, while you're at it? > > > > An inherent problem with using flash as a normal block device is that the > > flash erase size is bigger than most filesystem sector sizes. So when you > > request a write, it may erase and rewrite the next 64k, 128k, or even a couple > > megabytes on the really _big_ ones. > > > > If you lose power in the middle of that, ext3 won't notice that data in the > > "sectors" _after_ the one your were trying to write to got trashed. > > True enough, although the newer SSD's will have this problem addressed > (although at least initially, they are **far** more costly than the > el-cheapo 32GB SD cards you can find at the checkout counter at Fry's > alongside battery-powered shavers and trashy ipod speakers). Hey, I got one of those el-cheapo 32GB SD cards. I fully expected it to be slow, but eating my data 3 times per month was unexpected even for me. I'm not even sure where the blame is. I certainly blame the Linux documentation: there should be "DON'T USE CRAPPY SD CARDS" warning in big bold letters somewhere. I guess mkfs.ext3 should just refuse to make filesystem on them. (Of course, the manufacturer should have told me that the card is crap; I can bet it can not even work with VFAT/Windows). Plus I'd hope some filesystem materializes that can handle 128KB "block size"... because the el-cheapo card I have here is actually pretty sane. It seems to store data I put on it, and should be safe to use with huge block size... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html