Big Disk Performance Difference Between 13.04/14.10 and 14.04

[blind Pete]

Paul Brown wrote:

> I have three of the exact same dell r620 server (with a PERC H710 Mini
> raid controller) and I'm seeing disk performance differences across Ubuntu
> 13.04, 14.04, and 14.10.
> 
> Read speed is 100% *better *on 13.04 and 14.10 - compared to 14.04.
> Write speed is 50% *worse *on both 14.10 and 14.04 - compared to 13.04
> 
> More detail about the benchmarks is here:
> http://www.paulsprogrammingnotes.com/2015/01/slow-disk-performance-on-ubuntu-1304-vs.html
> 
> Does anyone know what is likely to cause this issue?

Wild stab in the dark: 

4k sector (mis) alignment?  

-- 
blind Pete
Sig goes here...