[CentOS] xfs not getting it right?

Wed Sep 20 14:57:27 UTC 2017
Chris Adams <linux at cmadams.net>

Once upon a time, hw <hw at gc-24.de> said:
> xfs is supposed to detect the layout of a md-RAID devices when creating the
> file system, but it doesn´t seem to do that:
> 
> 
> # cat /proc/mdstat
> Personalities : [raid1]
> md10 : active raid1 sde[1] sdd[0]
>       499976512 blocks super 1.2 [2/2] [UU]
>       bitmap: 0/4 pages [0KB], 65536KB chunk

RAID 1 has no "layout" (for RAID, that usually refers to striping in
RAID levels 0/5/6), so there's nothing for a filesystem to detect or
optimize for.

The chunk size above is for the md-RAID write-intent bitmap; that's not
exposed information (for any RAID system that I'm aware of, software or
hardware) or something that filesystems can optimize for.

-- 
Chris Adams <linux at cmadams.net>