On Thu, Feb 25, 2016 at 12:18 PM, Hegner Robert <rheg...@hsr.ch> wrote: >The idea with the btrfs-raid1 came from > (http://unix.stackexchange.com/a/186954) and it made perfect sense to me to > use a filesystem which is designed with flash-memory in mind and to use > raid1 to achieve some redundancy. But it looks like this was wrong > thinking...
I'd say Lionel is right in that these cards have a lot of reliability problems, but a big part of that is fake flash. You might test your cards to see if they are looping on themselves, i.e. lying about how big they really are and what happens is as they get only partly full they're really totally full and start overwriting themselves. If these two systems are essentially identically configured (same size flash, even if they aren't both raid1 configurations; and were setup on about the same day or week with the same kinds of workload being done) then it's plausible they both ran out of real space at the same time and face plant. For a GUI app that can test the flash quickly: https://blogs.gnome.org/hughsie/2015/01/28/detecting-fake-flash/ For CLI app that not as fast (it works differently, not sure if it's better or not), look for the F3 package. http://oss.digirati.com.br/f3/ I think if you find good quality flash your idea of using Btrfs raid1 either DUP or separate flash cards for embedded use is OK. I mean, it's what we have, even if it's not ideal. If it turns out there's some evidence a lot of flash out there totally face plants when the write pattern is substantially different than FAT32/64 then that suggests to me Btrfs needs a new (additional) ssd write allocator that more closely mimics FAT32 while still of course being COW and all that. But I suspect you've just got a bad batch of flash - I've got some PNY, Lexar, Kingston flash here that I use with Btrfs (for years now some of them) and don't have problems. And for development depending on Btrfs, I really do think you should consider a much newer kernel. Fedora 23 (current release) is on kernel 4.4.2 using the normal default stable updates repo. So it's not like you have to be adding on separate repos or manually installing packages to get new kernels. -- Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
