I need some clarification on what data you want collected.... do you want iostat -xm collected before and after?  Or at a periodic interval (1 sec)?

I'm measuring sustained performance.  This means I’m runnig for a period of time -- 1 minute.  If you want iostat collected on an interval, that would probably be more data than one would want posted to this mailing list.

But... yes, this is a RAID6.

I've switched to HDD's as storage as there is concern on the list that the DDR disk devices could be causing unintended behavior in RAID6.  With 6 HDD's, each able to do 270 MB/s on their outer edge, I'm getting RAID6 throughput of about 1080 MB/s when I use a thread count of 4, using FIO.

-----Original Message-----
From: Dallas Clement [mailto:dallas.a.clement@gmail.com] 
Sent: Friday, December 04, 2015 10:08 AM
To: Robert Kierski
Cc: Phil Turmel; linux-raid@vger.kernel.org
Subject: Re: RAID 5,6 sequential writing seems slower in newer kernels

Robert, is this with a RAID 6 array?  Also, what are the actual throughput numbers you are getting?  Would it be possible for you to capture the iostat -xm output and report the individual disk wMB/s and also the disk utilization for RAID 6?