ataraid(4) ATA software RAID support

SYNOPSIS

device ata device ataraid

DESCRIPTION

The 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 driver, so that Fx can work with the array. The 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 Fx 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 Fx 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 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 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

CAVEATS

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

AUTHORS

An -nosplit The driver was written by An Søren Schmidt Aq sos@FreeBSD.org . This manual page was written by An Christian Brueffer Aq brueffer@FreeBSD.org .