sunit & swidth on RAID-1?

[Justin Piszcz]

On Wed, 11 Feb 2009, mike dentifrice wrote:

> Justin Piszcz a dit:
>> mkfs.xfs will auto-optimize for software-raid arrays for the most
>> part,  with HW raid on a 3ware controller, tweaking mkfs.xfs does not
>> help very  much.  with SW raid, at least for raid1 - I use the
>> defaults.
>
> Thanks for your reply. However, I wonder about the defaults:
>
> 	xfs_info /dev/md1 | grep -E '(sunit|swidth)'
>
> Outputs:
>
>        sunit=0      swidth=0 blks, unwritten=1
>        sectsz=512   sunit=0 blks
>
> What's the consequence of 0 values in this case?
>
> Greetings,
>
> -- 
> mike dentifrice <fluor at poivron.org>
>

# xfs_info /dev/md2 | grep -E '(sunit|swidth)'
          =                       sunit=0      swidth=0 blks
          =                       sectsz=512   sunit=0 blks, lazy-count=0

Mine is similar, I guess you would need to benchmark to find out if you 
were worried about it.  I ran multiple copies from a RAID1 (dual raptors)
and was able to get the performance of both of the drives combine, so I am 
not really worried about this setting.

Justin.