freebsd-nq/share/man/man4/ataraid.4

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.Dd February 17, 2006
.Dt ATARAID 4
.Os
.Sh NAME
.Nm ataraid
.Nd "ATA software RAID support"
.Sh SYNOPSIS
.Cd "device ata"
.Cd "device ataraid"
.Sh DESCRIPTION
The
.Nm
driver provides support for so-called software RAID
(sometimes referred to as fake RAID or pseudo RAID).
.Pp
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
.Nm
driver, so that
.Fx
can work with the array.
The
.Nm
driver has to understand the specific metadata format of a
controller BIOS in order to support its RAID capabilities.
.Pp
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.
.Pp
Read and write support for a metadata format means that
.Fx
can use the given RAID array for normal read/write operations.
Additionally, the
.Xr atacontrol 8
utility can be used to create, rebuild, update and fail such
RAID arrays.
.Pp
The
.Nm
driver can read the following metadata formats:
.Pp
.Bl -bullet -compact
.It
Adaptec HostRAID
.It
Highpoint V2 RocketRAID
.It
Highpoint V3 RocketRAID
.It
Intel MatrixRAID
.It
Integrated Technology Express (ITE)
.It
JMicron
.It
LSI Logic V2 MegaRAID
.It
LSI Logic V3 MegaRAID
.It
NVIDIA MediaShield
.It
Promise FastTrak
.It
Silicon Image Medley
.It
Silicon Integrated Systems (SiS)
.It
VIA Tech V-RAID
.It
FreeBSD PseudoRAID
.El
.Pp
The
.Nm
driver can write the following metadata formats:
.Pp
.Bl -bullet -compact
.It
Highpoint V2 RocketRAID
.It
Intel MatrixRAID
.It
JMicron
.It
Promise FastTrak
.It
Silicon Integrated Systems (SiS)
.It
VIA Tech V-RAID
.It
FreeBSD PseudoRAID
.El
.Pp
It is also possible to use software RAID on controllers
that do not have special software RAID capabilities.
See
.Xr atacontrol 8
for details.
.Sh FILES
.Bl -tag -width ".Pa /dev/ar*" -compact
.It Pa /dev/ar*
ATA RAID device nodes
.El
.Sh SEE ALSO
.Xr ata 4 ,
.Xr atacontrol 8
.Sh CAVEATS
RAID5 is not supported at this time.
Code exists, but it neither uses nor maintains parity information. 
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An S\(/oren Schmidt Aq sos@FreeBSD.org .
This manual page was written by
.An Christian Brueffer Aq brueffer@FreeBSD.org .