On 02/07/2018 10:14 PM, NeilBrown wrote: > On Thu, Feb 08 2018, Wol's lists wrote: >> I've been playing with a mirror setup, and if we have two mirrors, we >> can rebuild any failed disk by coping from two other drives. I think >> also (I haven't looked at it) that you could do a fast rebuild without >> impacting other users of the system too much provided you don't swamp >> i/o bandwidth, as half of the requests for data on the three drives >> being used for rebuilding could actually be satisfied from other drives. > > I think that ends up being much the same result as a current raid10 > where the number of copies doesn't divide the number of devices. > Reconstruction reads come from 2 different devices, and half the reads > that would go to them now go elsewhere. This begs the question: Why not just use the raid10,near striping algorithm? Say one wants raid6 n=6 inside raid60 n=25. Use the raid10,near6 n=25 striping algorithm, but within each near6 inner stripe place data and P and Q using the existing raid6 rotation. What is the more complex placement algorithm providing? Phil -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
