Odd issue with mkfs.xfs under Lenny/amd64

[Robert Goley <ragoley@rdasys.com>]

I have not used xfs in a couple years but want to for a new server.  I 
have followed all the xfs documentation I could find.  I believe my 
commands are correct but am not seeing the results I expected from the 
documentation.  The issues occur with the sunit and swidth values.  I 
have a hardware raid5 array with 6 disks and a 256k strip size.  I have 
created a LVM volume using the -I option with 256k for the value.  I am 
creating the xfs filesystem with the following command:

"mkfs.xfs -f -b size=4096 -l size=128m -d 
sunit=512,swidth=2560,agsize=3g -L test /dev/raidvg/test"

It displays this info...
meta-data=/dev/raidvg/test       isize=256    agcount=34, agsize=786432 blks
        =                       sectsz=512   attr=2
data     =                       bsize=4096   blocks=26214400, imaxpct=25
        =                       sunit=64     swidth=320 blks
naming   =version 2              bsize=4096 
log      =internal log           bsize=4096   blocks=32768, version=2
        =                       sectsz=512   sunit=64 blks, lazy-count=0
realtime =none                   extsz=4096   blocks=0, rtextents=0

I tried mounting with with the command recommended below as well as 
without options.
mount -o sunit=512,swidth=2560,noatime,nodiratime,logbufs=8 
/dev/raidvg/test /test

Here are the results from xfs_info:
meta-data=/dev/mapper/raidvg-test isize=256    agcount=34, agsize=786432 
blks
        =                       sectsz=512   attr=2
data     =                       bsize=4096   blocks=26214400, imaxpct=25
        =                       sunit=64     swidth=320 blks
naming   =version 2              bsize=4096 
log      =internal               bsize=4096   blocks=32768, version=2
        =                       sectsz=512   sunit=64 blks, lazy-count=0
realtime =none                   extsz=4096   blocks=0, rtextents=0



As you can see, these values do not match the settings I told it to 
use.  If I use sunit=4096 and swidth=20480 values instead, It correctly 
shows the values I wanted in mkfs.xfs and xfs_info as long as I do not 
specify different values in the mount options.  Using "mount 
/dev/raidvg/test /test" or "mount -o 
sunit=4096,swidth=20480,noatime,nodiratime,logbufs=8 /dev/raidvg/test 
/test" it will show the values I expected to see for my setup.  Here is 
an xfs_info of those mounts.

meta-data=/dev/mapper/raidvg-test isize=256    agcount=34, agsize=786432 
blks
        =                       sectsz=512   attr=2
data     =                       bsize=4096   blocks=26214400, imaxpct=25
        =                       sunit=512    swidth=2560 blks
naming   =version 2              bsize=4096 
log      =internal               bsize=4096   blocks=32768, version=2
        =                       sectsz=512   sunit=64 blks, lazy-count=0
realtime =none                   extsz=4096   blocks=0, rtextents=0



Can anyone explain these results?  It does not match up with anything I 
have found on the web. 
Is this a bug?

Robert