LSI 9266-8i + 8x SSD RAID-0 - Limited to 800 MB/s

[jmginer]

Hello, I have a HP DL380 Gen7 and I have added a LSI 9266-8i in the reiser card.
Still using the HP original backplane and cables, but connected to the LSI instead to the origianl P410i.
I have added 8 x SSD Crucial M550.
Playing with many config options, but never can get more than 800MB/s in dd test.
I expected to get around 3 GB/s in RAID-0

This image is the test in RAID-0

Any idea?

CC/ @Patriot @mrkrad

Thanks.

 

[Patriot]

Are you using fastpath?
iflag=direct for read test, but I don't think it is needed for write tests.
Pcie 2.0 limits the bus to around 3GB/s of bandwidth but not as low as 800MBps...

I would try out FIO if I were you make sure dd isn't the problem... might just be a Qdepth problem.
Also, DD often has trouble with time... Try monitoring with IOstat and do a larger chunk ...

Disclaimer, I have disdain for micron/crucial drives...
Might want to check and make sure they are negotiating at 6Gbps those cables are close to max spec and I have seen signal integrity problems on M500 drives.

 

[Stanza]

What do you get for a larger block size?

Dd if=/dev/zero of=/array/ddtest bs=1024k count=10000

?