I know that the speculative prealloc of xfs can make files bigger on a 
destination, but I thought an "echo 3 >/proc/sys/vm/drop_caches" would 
help. I even umounted both filesystems, but the destination is bigger:

sys1 Blocks 8378368 Used 2631368 Avail 5747000
sys2 Blocks 8378368 Used 2966566 Avail 5411812

Both are VMs, have a 16G disk, partitioned same size, both on LVM, 
copied with rsync. xfs_info show the same for both:

meta-data=/dev/mapper/dns1--system-root isize=256    agcount=4, 
agsize=524288 blks
         =                       sectsz=512   attr=2
data     =                       bsize=4096   blocks=2097152, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal               bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

So why is there such a huge diff in size? 300M, 2.6G:2.9G, is a big 
number. I found these dirs to be very different:

( I rebooted here compared to results before, but same strangeness )
# du -s /1/usr/lib/locale/* /usr/lib/locale/*|sort -n|grep YU
20      /usr/lib/locale/sh_YU.utf8
1760    /1/usr/lib/locale/sh_YU.utf8

But comparing them directly, they are the same:

# du -s /1/usr/lib/locale/sh_YU.utf8 /usr/lib/locale/sh_YU.utf8
1760    /1/usr/lib/locale/sh_YU.utf8
1760    /usr/lib/locale/sh_YU.utf8

So what makes "du" show a huge different when the dir above gets 
scanned, versus when you compare dirs directly?