Hi all, How important are these read ahead settings for random, database IO? On 10/10/08, Ben Huang <ben_devel@yahoo.cn> wrote: > Hi all, > > --- Peter Keller <pkeller@globalphasing.com>写道: > >> Hi all, >> >> On Wed, 8 Oct 2008, thomas62186218@aol.com wrote: >> >> > Ben, >> > >> > I have seen this same issue as well. I have >> created an md device capable of >> > 425MB/sec using the hdparm -t command, yet an LVM >> volume fully comprising >> > this md device only got about 150MB/sec. I am not >> sure what the issue is. I >> > am running Ubuntu Hardy 804 server edition, >> 64-bit. >> > >> > -Thomas >> >> I have fixed this kind of problem by tweaking the >> readahead of the LVM >> volume using 'blockdev --setra' and/or 'blockdev >> --setfra'. > > It make effect > > > blockdev --setra 65536 /dev/md0 > blockdev --setra 65536 /dev/mapper/DG5-lv1 > > dd if=/dev/md0 of=/dev/null bs=1M > 353185562624 bytes (353 GB) copied, 420.033 s, 841 > MB/s > > dd if=/dev/mapper/DG5-lv1 of=/dev/null bs=1M > 155551006720 bytes (156 GB) copied, 216.576 s, 718 > MB/s > > Warm regards, > -Ben > > > ___________________________________________________________ > 雅虎邮箱，您的终生邮箱！ > http://cn.mail.yahoo.com/ > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ > -- Sent from my mobile device Eugene Vilensky evilensky@gmail.com _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
