relationship of nested stripe sizes, was: Question regarding XFS on LVM over hardware RAID.

[Chris Murphy]

Hopefully this is an acceptable way to avoid thread jacking, by renaming the  subject…

On Jan 30, 2014, at 10:58 PM, Stan Hoeppner <stan at hardwarefreak.com> wrote:
> 
> RAID60 is a nested RAID level just like RAID10 and RAID50.  It is a
> stripe, or RAID0, across multiple primary array types, RAID6 in this
> case.  The stripe width of each 'inner' RAID6 becomes the stripe unit of
> the 'outer' RAID0 array:
> 
> RAID6 geometry	 128KB * 12 = 1536KB
> RAID0 geometry  1536KB * 3  = 4608KB

My question is on this particular point. If this were hardware raid6, but I wanted to then stripe using md raid0, using the numbers above would I choose a raid0 chunk size of 1536KB? How critical is this value for, e.g. only large streaming read/write workloads? If it were smaller, say 256KB or even 32KB, would there be a significant performance consequence?

Chris Murphy