Interestingly enough, so far I'm finding with full stripe writes, i.e. 3x raid5, exactly 128KiB data writes, devid 3 is always parity. This is raid4. So...I wonder if some of these slow cases end up with a bunch of stripes that are effectively raid4-like, and have a lot of parity overwrites, which is where raid4 suffers due to disk contention.
Totally speculative as the sample size is too small and distinctly non-random. 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
