Untitled

root@scruffy:/# vgdisplay
  --- Volume group ---
  VG Name               lvm-raid
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  11
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               8.19 TiB
  PE Size               4.00 MiB
  Total PE              2146093
  Alloc PE / Size       0 / 0
  Free  PE / Size       2146093 / 8.19 TiB
  VG UUID               qtN3wM-fWyD-T3LN-WV4u-BXqU-50ym-uO72WF

root@scruffy:/# pvdisplay
  --- Physical volume ---
  PV Name               /dev/md0
  VG Name               lvm-raid
  PV Size               8.19 TiB / not usable 3.50 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              2146093
  Free PE               2146093
  Allocated PE          0
  PV UUID               nAXjk5-bb6J-QdKT-jiJ1-Khip-Q1Ky-7phI7m

root@scruffy:/# lvcreate -l +100%FREE lvm-raid -n media
  device-mapper: create ioctl on lvm--raid-media failed: Device or resource busy
  Failed to activate new LV.
root@scruffy:/# lvdisplay
root@scruffy:/# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid5 sdf1[4] sdd1[2] sdb1[1] sda1[0]
      8790400512 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/3] [UUU_]
      [==>..................]  recovery = 10.8% (317369856/2930133504) finish=429.7min speed=101334K/sec

unused devices: <none>