Ming Zhang wrote: >>component partitions, e.g. /dev/sda7: 39MB/s >>raid device /dev/md2: 31MB/s >>lvm device /dev/main/media: 53MB/s >> >>(oldish system - but note that lvm device is *much* faster) >> >> > >this is so interesting to see! seems that some read ahead parameters >have negative impact. > > I guess each raw device does some readahead, then the md0 does some readahead and then the lvm does some readahead. Theoretically the md0 and lvm should overlap - but I guess that much of the raw device level readahead is discarded. David -- - 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
