On Wed, 15 Jun 2011 23:35:53 +0900 Namhyung Kim <namhyung@xxxxxxxxx> wrote: > Namhyung Kim <namhyung@xxxxxxxxx> writes: > > 2011-06-15 (ì), 08:51 +0200, Keld JÃrn Simonsen: > >> On Wed, Jun 15, 2011 at 11:02:00AM +0900, Namhyung Kim wrote: > >> > If @conf->far_offset > 0, there is only 1 stripe so that we can treat > >> > the array same as 'near' arrays. > >> > >> does it also work with more than 2 copies - eg 3 copies? > >> I think the original code just takes the available data blocks with the > >> lowest address. > >> > > > > Hi, > > > > Let me clarify this: AFAIK, 'far offset' array saves redundant data in > > the diagonally adjacent chunk/disk, so it could be roughly thought as > > 'raid0' array with reduced size - just ignore redundant chunks here. It > > was my mistake considering it as 'near' array. :( > > > > I'm confused again. If fo > 0 && fc > 1 && nc > 1 then it turns out to > a near array with reduced size, no? Does it still need to be treaded > as RAID0? This would be a mix of near and offset. I'm not at all sure what the "best" read balancing approach would be. But as I don't think anyone would ever actually use it, I don't think it really matters. Thanks, NeilBrown > > > > Therefore, it makes more sense distributing reads over the array based > > on some criteria - here, the address of starting sector - like RAID0 > > does. Now I see that the same goes to the 'far copies' array exactly, so > > the original code is correct. > > > > Thanks. > -- > 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 -- 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
