stripe unit/width, inode64, misc mkfs.xfs params

[Peter Merelis]

Hi,
 
Apologies in advance as I imagine this issue is raised frequently, but can someone familiar with these sorts of things sanity check my stripe unit/width settings since the underlying storage controller is not exposing the data to mkfs.xfs apparently:
 
12 disk raid6
256k stripe
 
su=256k
sw=10
 
…which I believe is equivalent to:
 
sunit=512
swidth=5120
 
Is that correct?

Also, does the inode64 option make sense for a filesystem with only a few files, each around ~100G?

And finally, are 'allocsize=1GB,nobarrier,noatime,nodiratime' recommended mount options?
 
Thanks,
Peter