Novell LINUX ENTERPRISE SERVER 11 - STORAGE ADMINISTRATION GUIDE 2-23-2010, Administration Manual, Page: 92 / 140

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Table 10-3
Scenario for Creating a RAID 10 (1+0) by Nesting
1 Open a terminal console, then log in as the
root
user or equivalent.
2 Create 2 software RAID 1 devices, using two different devices for each RAID 1 device. At the
command prompt, enter these two commands:
mdadm --create /dev/md0 --run --level=1 --raid-devices=2 /dev/sdb1 /dev/
sdc1
mdadm --create /dev/md1 --run --level=1 --raid-devices=2 /dev/sdd1 /dev/
sde1
3 Create the nested RAID 1+0 device. At the command prompt, enter the following command
using the software RAID 1 devices you created in
Step 2 :
mdadm --create /dev/md2 --run --level=0 --chunk=64 --raid-devices=2 /dev/
md0 /dev/md1
The default chunk size is 64 KB.
4 Create a file system on the RAID 1+0 device
/dev/md2
, such as a Reiser file system (reiserfs).
For example, at the command prompt, enter
mkfs.reiserfs /dev/md2
Modify the command if you want to use a different file system.
5 Edit the
/etc/mdadm.conf
file to add entries for the component devices and the RAID device
/dev/md2
.
6 Edit the
/etc/fstab
file to add an entry for the RAID 1+0 device
/dev/md2
.
7 Reboot the server.
The RAID 1+0 device is mounted to
/local
.
10.2.3 Creating Nested RAID 10 (0+1) with mdadm
A nested RAID 0+1 is built by creating two to four RAID 0 (striping) devices, then mirroring them
as component devices in a RAID 1.
IMPORTANT: If you need to manage multiple connections to the devices, you must configure
multipath I/O before configuring the RAID devices. For information, see Chapter 7, “Managing
Multipath I/O for Devices,” on page 43 .
In this configuration, spare devices cannot be specified for the underlying RAID 0 devices because
RAID 0 cannot tolerate a device loss. If a device fails on one side of the mirror, you must create a
replacement RAID 0 device, than add it into the mirror.
The procedure in this section uses the device names shown in the following table. Make sure to
modify the device names with the names of your own devices.
Raw Devices RAID 1 (mirror) RAID 1+0 (striped mirrors)
/dev/sdb1
/dev/sdc1 /dev/md0
/dev/md2
/dev/sdd1
/dev/sde1 /dev/md1