Hi Paul, I have the same problem, I need to tune my disks to better performance. What protocol are you using? If you have it solve, please let me know. Thanks Nasc NetApp - Enjoy it! On Fri, May 14, 2010 at 1:43 PM, Paul Raines <raines@xxxxxxxxxxxxxxxxxxx> wrote: > > Sorry if this is the wrong contact to ask this > > I am running RHEL 5.5 w/ device-mapper-multipath-0.4.7-34.el5 > > I am trying to tune my disks for better performance with the settings > > echo 2048 > /sys/block/$bdev/queue/read_ahead_kb > echo 64 > /sys/block/$bdev/queue/nr_requests > echo deadline > /sys/block/$bdev/queue/scheduler > echo 8192 > /sys/block/$bdev/queue/max_sectors_kb > > On the individual disk when I do this I get a big jump in read performance > of nearly 2x > > # dd if=/dev/sdig bs=1024k of=/dev/null skip=3000 count=3000 > 3000+0 records in > 3000+0 records out > 3145728000 bytes (3.1 GB) copied, 13.8672 seconds, 227 MB/s > > # dd if=/dev/sdig bs=1024k of=/dev/null skip=9000 count=3000 > 3000+0 records in > 3000+0 records out > 3145728000 bytes (3.1 GB) copied, 7.70806 seconds, 408 MB/s > > So /dev/sdig is part of a multipath > > # ls -l /sys/block/dm-119/slaves/ > total 0 > lrwxrwxrwx 1 root root 0 May 14 12:14 sdez -> ../../../block/sdez > lrwxrwxrwx 1 root root 0 May 14 12:14 sdif -> ../../../block/sdif > > I apply the tuning to both sdez and sdif, however, when I do the > dd read test on the dm device, it is still slow > > # dd if=/dev/dm-119 bs=1024k of=/dev/null skip=18000 count=3000 > 3000+0 records in > 3000+0 records out > 3145728000 bytes (3.1 GB) copied, 15.1546 seconds, 208 MB/s > > Fine, I need to apply the tuning to the dm-119 device itself. But there > is no queue sub dir in /sys/block/dm-119 > > # ls /sys/block/dm-119 > dev holders range removable size slaves stat subsystem uevent > > > So how do I tune the multipath device itself? > > -- > --------------------------------------------------------------- > Paul Raines email: raines at nmr.mgh.harvard.edu > MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging > 149 (2301) 13th Street Charlestown, MA 02129 USA > > > -- > dm-devel mailing list > dm-devel@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/dm-devel > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
