Software raid

Today I connected SDD hard drive to my new server. Because it contains 4 memory drives I decided to use software raid to use it as one huge free space.

root@alucard:/home/shamrock# mdadm --create /dev/md0 \
-f -v -l 0 -n 4 /dev/dm-1 /dev/dm-2 /dev/dm-3 /dev/dm-4

mdadm: chunk size defaults to 512K
mdadm: /dev/sdb appears to be part of a raid array:
    level=raid0 devices=0 ctime=Thu Jan  1 00:00:00 1970
mdadm: partition table exists on /dev/sdb but will be lost or
       meaningless after creating array
mdadm: /dev/sdc appears to be part of a raid array:
    level=raid0 devices=0 ctime=Thu Jan  1 00:00:00 1970
mdadm: partition table exists on /dev/sdc but will be lost or
       meaningless after creating array
mdadm: /dev/sdd appears to be part of a raid array:
    level=raid0 devices=0 ctime=Thu Jan  1 00:00:00 1970
mdadm: partition table exists on /dev/sdd but will be lost or
       meaningless after creating array
mdadm: /dev/sde appears to be part of a raid array:
    level=raid0 devices=0 ctime=Thu Jan  1 00:00:00 1970
mdadm: partition table exists on /dev/sde but will be lost or
       meaningless after creating array
Continue creating array? y
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
root@alucard:/home/shamrock# mkfs.xfs /dev/md0 
log stripe unit (524288 bytes) is too large (maximum is 256KiB)
log stripe unit adjusted to 32KiB
meta-data=/dev/md0               isize=256    agcount=32, agsize=9157376 blks
         =                       sectsz=512   attr=2, projid32bit=0
data     =                       bsize=4096   blocks=293036032, imaxpct=5
         =                       sunit=128    swidth=512 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=143088, version=2
         =                       sectsz=512   sunit=8 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0


root@alucard:/home/shamrock# df -h
Filesystem            Size  Used Avail Use% Mounted on
rootfs                 12G  2.6G  9.5G  22% /
udev                   95G  132K   95G   1% /dev
tmpfs                  19G  2.3M   19G   1% /run
/dev/mapper/lvm0-dom0
                       12G  2.6G  9.5G  22% /
tmpfs                 5.0M     0  5.0M   0% /run/lock
tmpfs                  38G   10M   38G   1% /tmp
tmpfs                  38G  4.0K   38G   1% /run/shm
/dev/mapper/lvm0-base
                      2.6T  2.4T  238G  91% /base
/dev/md0              1.1T   34M  1.1T   1% /media/md0