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ATARAID(4)		     Kernel Interfaces Manual		      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 under-
     stand 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 ata-
     control(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)

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

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

FreeBSD 8.3			February 17, 2006		      ATARAID(4)

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