database & big files

for raid:
mkfs.xfs -d sunit=xxx,swidth=xxx
  sunit = strip_size(byte) / 512
  swidth = sunit * nr_raid_disks

mount option:
noatime,nodiratime,allocsize=128M
  allocsize help reduce fragmentation

frag check:
xfs_bmap /path/to/file
xfs_db -c frag -r /dev/sda3

defrag:
xfs_fsr -t 3600

reference