Hi,
What command did you use to create your raid-10? You might try
running iostat in parallel to see if the read_balancer is properly
balancing the reads between the two disks.
I've seen situations where raid-10 on sequential reads will pretty
much always prefer the same disk and barely use the mirror.
One thing we looked at was changing to the far layout, which helped
a bit.
--Rob
On Oct 16, 2009, at 10:32 AM, adfas asd wrote:
> I was hoping to get better performance with RAID10 than from the raw
> disks, but that's turned out to not be the case. Experimenting with
> the readahead buffer I get these bandwidths with the following
> command:
> # time dd if={somelarge}.iso of=/dev/null bs={readahead size}
>
> /dev/sd?
> 1024 71.3 MB/s
> 2048 71.2 MB/s
> 4096 77.7 MB/s
> 8192 69.4 MB/s
> 16384 76.6 MB/s
>
> /dev/md2
> 1024 67.1
> 2048 69.1
> 4096 75.7
> 8192 64.9
> 16384 69.0
>
> Using RAID10offset2 on 2 WD 2TB drives, and always the same input
> file.
>
> Why would RAID10 performance be -poorer-?
> If it weren't for mirroring, this wouldn't be worth it.
>
>
>
>
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-
> raid" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
