не долго думая создал (в первый раз) рейд 5
mdadm --create --verbose /dev/md1 --level=5 --raid-devices=6 /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg /dev/sdh
md1 : active raid5 sdh[6] sdg[4] sdf[3] sde[2] sdd[1] sdc[0]
4883156480 blocks super 1.2 level 5, 512k chunk, algorithm 2 [6/5] [UUUUU_]
[====>................] recovery = 23.3% (227639680/976631296) finish=1363.9min speed=9152K/sec
bitmap: 1/8 pages [4KB], 65536KB chunk
# mdadm --query --detail /dev/md1
/dev/md1:
Version : 1.2
Creation Time : Wed Apr 5 10:55:56 2017
Raid Level : raid5
Array Size : 4883156480 (4656.94 GiB 5000.35 GB)
Used Dev Size : 976631296 (931.39 GiB 1000.07 GB)
Raid Devices : 6
Total Devices : 6
Persistence : Superblock is persistent
Intent Bitmap : Internal
Update Time : Wed Apr 5 15:58:09 2017
State : active, degraded, recovering
Active Devices : 5
Working Devices : 6
Failed Devices : 0
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 512K
Rebuild Status : 23% complete
Name : s1:1 (local to host s1)
UUID : c59f91ba:1683a43c:9a0d81f2:f058dd2b
Events : 40725
Number Major Minor RaidDevice State
0 8 32 0 active sync /dev/sdc
1 8 48 1 active sync /dev/sdd
2 8 64 2 active sync /dev/sde
3 8 80 3 active sync /dev/sdf
4 8 96 4 active sync /dev/sdg
6 8 112 5 spare rebuilding /dev/sdh