Peter Rabbitson wrote:
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
This is incorrect. Only the readahead setting of the _last_ block device
matters. So in case you have a raid6 of 10 drives, with LUKS on top,
with LVM on top - only the readahead settings of the individual LVs
matter, nothing further down the chain is consulted.
I have some old numbers which indicate that with ext3 the use of
"stride=" can improve performance, although I was measuring write and
just got the read numbers without really caring about them.
--
Bill Davidsen <davidsen@xxxxxxx>
"Woe unto the statesman who makes war without a reason that will still
be valid when the war is over..." Otto von Bismark
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