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

     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.