Next, use the above configuration and the
mdadm
command to create a RAID 0 array:
mdadm -C /dev/md0 --level=raid0 --raid-devices=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:
Version : 00.90.00
Creation Time : Mon Mar
1 13:49:10 2004
Raid Level : raid0
Array Size : 15621632 (14.90 GiB 15.100 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Mon Mar
1 13:49:10 2004
State : dirty, no-errors
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Chunk Size : 64K
Number
Major
Minor
RaidDevice State
0
8
1
0
active sync
/dev/sda1
1
8
17
1
active sync
/dev/sdb1
2
8
33
2
active sync
/dev/sdc1
3
8
49
3
active sync
/dev/sdd1
UUID : 25c0f2a1:e882dfc0:c0fe135e:6940d932
Events : 0.1
3.2. Creating a Multipath Device With
mdadm
In addition to creating RAID arrays,
mdadm
can also be used to take advantage of hardware
supporting more than one I/O path to individual SCSI LUNs (disk drives). The goal of multipath
storage is continued data availability in the event of hardware failure or individual path
saturation. Because this configuration contains multiple paths (each acting as an independent
virtual controller) accessing a common SCSI LUN (disk drive), the Linux kernel detects each
shared drive once "through" each path. In other words, the SCSI LUN (disk drive) known as
/dev/sda
may also be accessible as
/dev/sdb
,
/dev/sdc
, and so on, depending on the
specific configuration.
Appendix F. Additional Information for S/390 and zSeries Users
70
Summary of Contents for ENTERPRISE LINUX 3 - FOR IBM S-390 AND IBM ESERVER ZSERIES
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