Daniel Pittman wrote:
With the raid-0 running, doing a dd if=/dev/md1 of=/dev/null I get about 55MB/s read speed.
I can't quite figure out why the md is so slow. Given its using streaming reads with no seeking it should be over 100MB/s.
Your chunk size is way to low to give good streaming reads. The kernel needs to switch between devices every 128 kilobytes, while is rather low.
Try slowly pushing the chunk size to 16384 and see when your performance gets back up to your expected level.
Nope.. Any chunk size > 4096 gives me too big chunk_size: 8388608 > 4194303.
And the performance difference between chunk=16 and chunk=4096 is less than 5MB/s
--chunk=16 gives me 48.43 MB/s --chunk=4096 gives me 51.52 MB/s
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