The software described in this documentation is either in Extended Support or Sustaining Support. See https://www.oracle.com/us/support/library/enterprise-linux-support-policies-069172.pdf for more information.
Oracle recommends that you upgrade the software described by this documentation as soon as possible.
To create a software RAID device:
Use the mdadm command to create the MD RAID device:
#
mdadm --create
md_device
--level=
RAID_level
[options
]--raid-devices=
N
device
...For example, to create a RAID-1 device
/dev/md0
from/dev/sdf
and/dev/sdg
:#
mdadm --create /dev/md0 --level=1 -raid-devices=2 /dev/sd[fg]
Create a RAID-5 device
/dev/md1
from/dev/sdb
,/dev/sdc
, anddev/sdd
:#
mdadm --create /dev/md1 --level=5 -raid-devices=3 /dev/sd[bcd]
If you want to include spare devices that are available for expansion, reconfiguration, or replacing failed drives, use the --spare-devices option to specify their number, for example:
#
mdadm --create /dev/md1 --level=5 -raid-devices=3 --spare-devices=1 /dev/sd[bcde]
NoteThe number of RAID and spare devices must equal the number of devices that you specify.
Add the RAID configuration to
/etc/mdadm.conf
:#
mdadm --examine --scan >> /etc/mdadm.conf
NoteThis step is optional. It helps mdadm to assemble the arrays at boot time.
For example, the following entries in
/etc/mdadm.conf
define the devices and arrays that correspond to/dev/md0
and/dev/md1
:DEVICE /dev/sd[c-g] ARRAY /dev/md0 devices=/dev/sdf,/dev/sdg ARRAY /dev/md1 spares=1 devices=/dev/sdb,/dev/sdc,/dev/sdd,/dev/sde
For more examples, see the sample configuration file
/usr/share/doc/mdadm-3.2.1/mdadm.conf-example
.
Having created an MD RAID device, you can configure and use it in the same way as you would a physical storage device. For example, you can configure it as an LVM physical volume, file system, swap partition, Automatic Storage Management (ASM) disk, or raw device.
You can view /proc/mdstat
to check the status
of the MD RAID devices, for example:
# cat /proc/mdstat
Personalities : [raid1]
mdo : active raid1 sdg[1] sdf[0]
To display summary and detailed information about MD RAID devices, you can use the --query and --detail options with mdadm.
For more information, see the md(4)
,
mdadm(8)
, and
mdadm.conf(5)
manual pages.