System information

dmraid
Device-mapper RAID or d mrai d refers to device-mapper kernel code that offers the mechanism to
piece disks together into a RAID set. This same kernel code does not provide any RAID configuration
mechanism.
d mrai d is configured entirely in user-space, making it easy to support various on-disk metadata
formats. As such, d mrai d is used on a wide variety of firmware RAID implementations. d mrai d also
supports Intel firmware RAID, although Red Hat Enterprise Linux 6 uses md rai d to access Intel
firmware RAID sets.
17.4. RAID Support in t he Inst aller
The Anaco n d a installer will automatically detect any hardware and firmware RAID sets on a system,
making them available for installation. An acond a also supports software RAID using md rai d , and
can recognize existing md rai d sets.
An aco n da provides utilities for creating RAID sets during installation; however, these utilities only
allow partitions (as opposed to entire disks) to be members of new sets. To use an entire disk for a
set, simply create a partition on it spanning the entire disk, and use that partition as the RAID set
member.
When the root file system uses a RAID set, An aco n d a will add special kernel command-line options
to the bootloader configuration telling the i ni trd which RAID set(s) to activate before searching for
the root file system.
For instructions on configuring RAID during installation, refer to the Red Hat Enterprise Linux 6
Installation Guide.
17.5. Configuring RAID Set s
Most RAID sets are configured during creation, typically through the firmware menu or from the
installer. In some cases, you may need to create or modify RAID sets after installing the system,
preferably without having to reboot the machine and enter the firmware menu to do so.
Some hardware RAID controllers allow you to configure RAID sets on-the-fly or even define
completely new sets after adding extra disks. This requires the use of driver-specific utilities, as there
is no standard API for this. Refer to your hardware RAID controller's driver documentation for
information on this.
mdadm
The md ad m command-line tool is used to manage software RAID in Linux, i.e. md rai d . For
information on the different md ad m modes and options, refer to man md ad m. The man page also
contains useful examples for common operations like creating, monitoring, and assembling software
RAID arrays.
dmraid
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