On 3/3/2012 6:56 PM, Steven Haigh wrote: > On 4/03/2012 8:42 AM, Stan Hoeppner wrote: [snip] >>> blockdev --setra 8192 /dev/sd[abcdefg] >> >> Read-ahead is per file descriptor, and occurs at the filesystem level. >> The read-ahead value used is that of the device immediately underlying >> the filessytem. So don't bother setting these above. > > Interesting - I didn't think that was the case for whole disk arrays - > but there you go... Learnt something else :) [snip] >>> echo 4096> /sys/block/$i/queue/read_ahead_kb >> Eliminate this line ^^^^ > > Any insight into why? I would have thought that this would help - > however I'm not quite sure as to the values - as this is much less than > one chunk... That also being said, wouldn't it be a good idea to have > *some* readahead? You read the answer up above, and commented on it. Maybe you didn't fully understand? Or maybe it's because you don't know that these two are functionally equivalent? blockdev --setra X echo X > /sys/block/$i/queue/read_ahead_kb -- Stan -- 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
