thomas62186218@xxxxxxx wrote:
Hi everyone,
I too was seeing miserable read-performance with LVM2 volumes on top of
md RAID 10's on my Ubuntu 8.04 64-bit machine. My RAID 10 has 12 x 300GB
15K SAS drives on a 4-port LSI PCIe SAS controller.
I use:
blockdev --setra 65536 /dev/md0
And this dramatically increased my RAID 10 read performance.
You MUST do the same for your LVM2 volumes for them to see a comparable
performance boost.
blockdev --setra 65536 /dev/mapper/raid10-testvol
Otherwise, your LVM will default to 256 read-ahead value, which stinks.
I increased my read performance by 3.5x with this one change! See below:
Yea, that's the general idea, besides proper alignment. It wokred nice
for Holger as well. Specifying (popular for some reason) 65536 is quite
an overkill though, imho.
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