2006/1/18, Mario 'BitKoenig' Holbe <Mario.Holbe@xxxxxxxxxxxxx>: > Mario 'BitKoenig' Holbe <Mario.Holbe@xxxxxxxxxxxxx> wrote: > > scheduled read-requests. Would it probably make sense to split one > > single read over all mirrors that are currently idle? > > A I got it from the other thread - seek times :) > Perhaps using some big (virtual) chunk size could do the trick? What > about using chunks that big that seeking is faster than data-transfer... > assuming a data rate of 50MB/s and 9ms average seek time would result in > at least 500kB chunks, 14ms average seek time would result in at least > 750kB chunks. > However, since the blocks being read are most likely somewhat close > together, it's not a typical average seek, so probably smaller chunks > would also be possible. > > > regards > Mario Stop me if I'm wrong, but this is called... huge readahead. Instead of reading 32k on drive0 then 32k on drive1, you read continuous 512k from drive0 (16*32k) and 512k from drive1, resulting in a 1M read. Maybe for a single 4k page... So my additionnal question to this would be : how well does md fit with linux's/fs readahead policies ? - 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
