søn, 18 03 2007 kl. 16:34 +0000, skrev Andy Burns: > I have an F7/rawhide machine with 6x400GB SATA II disks all > partitioned as 100MB + 399.9GB > > /boot is on /dev/sda1 (would be RAID1 across /dev/sd[abc]1 partitions > except for mkinitrd raid1.ko breakage) with /dev/md1 as RAID5 on > /dev/sd[abcdef]2 > > Then a single LVM vg00 on top of /dev/md1 > > root and swap as LVs within vg00 and plenty of spare space. > > Doing some timings of the various block devices (so far just roughly > with hdparm, bonnie installed for more detail later). Results of > "hdparm -Tt" averaged over a few runs, showing cached and buffered > speeds > > /dev/sda1 gives 1995MB/s and 72MB/s which seems quite good for a single spindle > /dev/md1 gives 2040MB/s and 260MB/s also fairly good (I had hoped with > six spindles and parity to get closer to 5x performance than 3.5x) > /dev/mapper/vg00-lv01 (my root fs) gives 2100MB/s and 135MB/s which is > a little disappointing > > Nearly a 50% speed penalty seems a heavy price to pay for LVM, is > there any slow debug code currently in rawhide that might explain it? > Could I have some bad choices of block sizes between RAID/LVM layers > which are reducing throughput by splitting reads? Anything else? Wow that explains a lot.. performance on Development has be awful for me lately and I have been unable to figure out why, this might be related. My setup is 2 400GB drives in RAID0 using dmraid with LVM ontop. - David Nielsen -- "Ridicule is the only weapon that can be used against unintelligible propositions. Ideas must be distinct before reason can act upon them.” -Thomas Jefferson
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