ATARAID(4)

NAME
ataraid - ATA software RAID support

SYNOPSIS
device ata
device ataraid

DESCRIPTION
The ataraid driver provides support for so-called software RAID (sometimes referred to as fake RAID or pseudo RAID).

When a controller that supports software RAID is instructed to create a RAID array, its BIOS writes data structures in a specific metadata format to the disks. These data structures are picked up by the ataraid driver, so that FreeBSD can work with the array. The ataraid driver has to understand the specific metadata format of a controller BIOS in order to support its RAID capabilities.

Read-only support for a metadata format means that FreeBSD can use the given RAID array for normal read/write operations. Creation and rebuild of such arrays has to be done from the controller BIOS.

Read and write support for a metadata format means that FreeBSD can use the given RAID array for normal read/write operations. Additionally, the atacontrol(8) utility can be used to create, rebuild, update and fail such RAID arrays.

The ataraid driver can read the following metadata formats:

•   Adaptec HostRAID
•   Highpoint V2 RocketRAID
•   Highpoint V3 RocketRAID
•   Intel MatrixRAID
•   Integrated Technology Express (ITE)
•   JMicron
•   LSI Logic V2 MegaRAID
•   LSI Logic V3 MegaRAID
•   NVIDIA MediaShield
•   Promise FastTrak
•   Silicon Image Medley
•   Silicon Integrated Systems (SiS)
•   VIA Tech V-RAID
•   FreeBSD PseudoRAID

The ataraid driver can write the following metadata formats:

•   Highpoint V2 RocketRAID
•   Intel MatrixRAID
•   JMicron
•   Promise FastTrak
•   Silicon Integrated Systems (SiS)
•   VIA Tech V-RAID
•   FreeBSD PseudoRAID

It is also possible to use software RAID on controllers that do not have special software RAID capabilities. See atacontrol(8) for details.

FILES
/dev/ar*
    ATA RAID device nodes

SEE ALSO
ata(4), atacontrol(8)

AUTHORS
-nosplit The ataraid driver was written by Søren Schmidt <sos@FreeBSD.org>. This manual page was written by Christian Brueffer <brueffer@FreeBSD.org>.

CAVEATS
RAID5 is not supported at this time. Code exists, but it neither uses nor maintains parity information.