Hi, > > But this setup was too complicated for me, so I tried a different > > approach. Still a physical volume for each disk (actually partiton 2 > > which is nearly the complete disk), but only one volume group vg0. > > The commands used were: > > > > pvcreate /dev/sda2 > > pvcreate /dev/sdb2 > > pvcreate /dev/sdc2 > > vgcreate vg0 -s 128 /dev/sda2 /dev/sdb2 /dev/sdc2 > > > > On vg0, I created a LV which should span all 3 disks and therefore be > > equivalent to a RAID 0: > > > > lvcreate --name=test -L 10000M -i 3 vg0 > > > > Resulting LV: > > > > --- Logical volume --- LV Name /dev/vg0/ubuntu VG Name vg0 > > LV Write Access read/write > > LV Status available > > # open 1 > > LV Size 10,12 GB > > Current LE 81 > > Segments 1 > > Allocation inherit > > Read ahead sectors 0 > > Block device 254:10 > > > > However, I get only half the expected performance. I created an XFS > > filesystem and mounted it on /mnt/tmp: > > > > # dd if=/dev/zero of=/mnt/tmp/bla bs=1024k count=10000 > > 10485760000 Bytes (10 GB) kopiert, 112,233 Sekunden, 93,4 MB/s > > # dd if=/mnt/tmp/bla of=/dev/null bs=1024k count=10000 > > 10485760000 Bytes (10 GB) kopiert, 88,8886 Sekunden, 118 MB/s > > > > This was measured with kernel 2.6.23.12 and 2.6.25.1 on AMD64 X2. > > Is it possible to get 210 MB/s? > > Have you tried fiddling with read ahead ? > "blockdev --setra ..." on the striped LV. read ahead is currently 256 on all devices. Thanks for the hint. I will try some other values. Any Idea what is recommended? Thanks, hjb -- Pro-Linux - Germany's largest volunteer Linux support site http://www.pro-linux.de/ Public Key ID 0x3DDBDDEA
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