On Tue, May 11, 2010 at 7:09 AM, Marco Peereboom <sl...@peereboom.us> wrote: > Sure, but why? > > What are we gaining?
So to be clear, I wasn't as much saying softraid *should* switch. I was just casually reading the code, saw the comment about "left asymmetric layout", and so I started investigating what that meant and what the other options were. I've found very little documentation explaining the technical merits of the different layouts, except that symmetric layouts have slightly more even distribution of contiguous data stripes across the array. (E.g., for a 3-disk RAID 5 array, with a symmetric layout, every 3 contiguous data stripes will have one stripe on each disk, while an asymmetric layout sometimes 3 contiguous data stripes will only be distributed across two of the three disks.) It's perhaps not a significant difference (and unfortunately, I don't have the hardware to test), but as I haven't found any analogous mention of advantages (even weak ones) for an asymmetric layout, I was just curious why one was chosen and thought I'd ask.
