Re: RAIDframe and alignment on 4K-sector disks?

[Patrick Welche <prlw1%cam.ac.uk@localhost>]

On Mon, Jun 12, 2017 at 01:44:56AM -0500, John D. Baker wrote:
> On Mon, 12 Jun 2017 04:55:52 -0000 (UTC), mlelstv%serpens.de@localhost (Michael
> van Elst) wrote:
> 
> > Currently best practice for such a RAID is:
> >  
> > -> align the RAID partition(s) on each component to 4k
> 
> A given.  That's all these components are going to do, so 0 % 8 == 0.
> 
> > -> use a stripe size of 64k (maxphys), with RAID-5 on 3 disks that's
> >    SecPerSU=64 (parity doesn't count).
> 
> Doesn't RAIDframe assume 512-byte sectors?  So, 64k stripe size would
> be SecPerSU=128, yes?

I think it's SecPerSU=64 blocks = 32k. Two data disks in one write, so
2 * 32k = 64k = MAXPHYS written in one write.

(Please correct me if I'm wrong: I just make a 3 * 2T raid 5 this morning ;-) )

Cheers,

Patrick