Re: mkfs.xfs -d su=XXX,sw=YYY and future volume resize

[Dave Chinner <david@xxxxxxxxxxxxx>]

On Thu, Jul 14, 2016 at 10:19:02PM +0200, Marcin Sura wrote:
> Hi,
> 
> When I create filesystem I can specify su and sw paramteres which match
> underlying storage device.
> So for example, If I have raid 6 volume made of 6 + 2 disks with stripe
> size of 256k I create xfs with:
> 
> mkfs.xfs -d su=256k,sw=6 <disk>
> 
> But what if I will extend original volume by 2 disks. sw will 8. Will be
> there a performance panelty compared to filesystem created from scratch
> with correct sw parameter?

That depends on your workload more than anything. If the workload
benefits from correct stripe alignment of your data and IO, then it
will definitely perform worse if you change the stripe width so that
allocation is no longer able to align correctly to the physical
geometry of the storage.

-Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx