26.06.2016 00:52, Chris Murphy пишет: > 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. That's not what code suggests and what I see in practice - parity seems to be distributed across all disks; each new 128KiB file (extent) has parity on new disk. At least as long as we can trust btrfs-map-logical to always show parity as "mirror 2". Do you see consecutive full stripes in your tests? Or how do you determine which devid has parity for a given full stripe? This information is not actually stored anywhere, it is computed based on block group geometry and logical stripe offset. P.S. usage of "stripe" to mean "stripe element" actually adds to confusion when reading code :) -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
