Creating A Multipath Device With; Mdadm - Red Hat ENTERPRISE LINUX 4 - INSTALLATION GUIDE FOR IBM S-390 AND IBM ESERVER ZSERIES Installation Manual

Appendix F. Additional Information for S/390 and zSeries Users
Next, use the above configuration and the
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
/dev/md0:
Version : 00.90.00
Creation Time : Mon Mar
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
State : dirty, no-errors
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Chunk Size : 64K
Number Major
0
1
2
3
UUID : 25c0f2a1:e882dfc0:c0fe135e:6940d932
Events : 0.1

3.2. Creating a Multipath Device With

In addition to creating RAID arrays,
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
may also be accessible as
/dev/sda
specific configuration.
70

mdadm

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Minor RaidDevice State
8 1
8 17
8 33
8 49
can also be used to take advantage of hardware
mdadm
/dev/sdb
command to create a RAID 0 array:
mdadm --detail /dev/md0
0 active sync
1 active sync
2 active sync
3 active sync
mdadm
, , and so on, depending on the
/dev/sdc
:
/dev/sda1
/dev/sdb1
/dev/sdc1
/dev/sdd1