On 4/03/2012 1:24 PM, Stan Hoeppner wrote:
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/$i/queue/read_ahead_kbEliminate this line ^^^^Any insight into why? I would have thought that this would help - however I'm not quite sure as to the values - as this is much less than one chunk... That also being said, wouldn't it be a good idea to have *some* readahead?You read the answer up above, and commented on it. Maybe you didn't fully understand? Or maybe it's because you don't know that these two are functionally equivalent? blockdev --setra X echo X> /sys/block/$i/queue/read_ahead_kb
Ahhh - you're spot on... I didn't think they had the same functionality! -- Steven Haigh Email: netwiz@xxxxxxxxx Web: http://www.crc.id.au Phone: (03) 9001 6090 - 0412 935 897 Fax: (03) 8338 0299
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