Red Hat ENTERPRISE LINUX 5 - VIRTUAL SERVER ADMINISTRATION, Руководство по установке

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Using
mdadm
to Configure RAID-Based and Multipath Storage
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22.3. Using
mdadm
to Configure RAID-Based and Multipath
Storage
Similar to other tools comprising the
raidtools
package set, the
mdadm
command can be used to
perform all the necessary functions related to administering multiple-device sets. This section explains
how
mdadm
can be used to:
• Create a RAID device
• Create a multipath device
22.3.1. Creating a RAID Device With
mdadm
To create a RAID device, edit the
/etc/mdadm.conf
file to define appropriate
DEVICE
and
ARRAY
values:
DEVICE ­/dev/sd[abcd]1
ARRAY ­/dev/md0 devices=/dev/sda1,/dev/sdb1,/dev/sdc1,/dev/sdd1
In this example, the
DEVICE
line is using traditional file name globbing (refer to the
glob
(7) man page
for more information) to define the following SCSI devices:
•
/dev/sda1
•
/dev/sdb1
•
/dev/sdc1
•
/dev/sdd1
The
ARRAY
line defines a RAID device (
/dev/md0
) that is comprised of the SCSI devices defined by
the
DEVICE
line.
Prior to the creation or usage of any RAID devices, the
/proc/mdstat
file shows no active RAID
devices:
Personalities ­:
read_ahead not set
Event: 0
unused devices: none
Next, use the above configuration and the
mdadm
command to create a RAID 0 array:
mdadm ­­C ­/dev/md0 ­­­level=raid0 ­­­raid­devices=4 ­/dev/sda1 ­/dev/sdb1 ­/dev/sdc1 \
/dev/sdd1
Continue creating array? yes
mdadm: array ­/dev/md0 started.
Once created, the RAID device can be queried at any time to provide status information. The following
example shows the output from the command
mdadm --detail /dev/md0
:
/dev/md0: