> So, the mirroring turns a single large write into two large writes. > Definitely not free, but always a fixed cost. Thanks for the explanation and the numbers. I see that's the advantage of copy-on-write that you can actually always cluster the metadata together and get always batched IO this way and then afford to do more of it. Still wondering what that will do to read seekiness. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html