> do on a regular basis) that running with barriers over power fail > testing gets you a solid recovery. Running with write cache on and no > barriers gets you file system corruption. in short "barriers work". never doubted! > As I said before, the data you > just wrote (or the file system wrote for you) most recently is the same > data that you stand to lose on a powerloss. obviously. so the question is whether the cache still has dirty writeback when the power drops due to normal poweroff. I'd consider it a bug in the laptop bios to let this happen, but that's not going to make the affected user happy... > If there is a hole in the sequence, dropping to standby could be the > source of issues... I guess it's a matter of how byzantine the bugs are you want to consider. for mass-produced devices, I'm reluctant to assume the disk vendor has forgotten to _ever_ flush writeback data, for instance. and don't forget that a bogus drive that entirely forgets writeback may also not really turn off write caching when you tell it to! I assume that the disk will indeed do writeback if left idle for a little while. on machines where this is a real problem, I would start out by waving relevant chickens like the following to give the best chance of shutting down cleanly: sync blockdev --flushbufs hdparm -W 0 sleep 2 hdparm -y sleep 5 halt -hp rather than _always_ suffering the penalty of disabled write cache, especially on a single slow laptop drive... - : send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
