x86_64: Fix a warning.

[dragonfly.git] / sbin / ccdconfig / ccdconfig.8

.\"     $NetBSD: ccdconfig.8,v 1.1.2.1 1995/11/11 02:43:33 thorpej Exp $
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.\" Copyright (c) 1995 Jason R. Thorpe.
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.\"     This product includes software developed for the NetBSD Project
.\"     by Jason R. Thorpe.
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.\" $FreeBSD: src/sbin/ccdconfig/ccdconfig.8,v 1.9.2.10 2003/01/26 03:38:39 keramida Exp $
.\" $DragonFly: src/sbin/ccdconfig/ccdconfig.8,v 1.7 2008/05/02 02:05:05 swildner Exp $
.\"
.Dd February 8, 2009
.Dt CCDCONFIG 8
.Os
.Sh NAME
.Nm ccdconfig
.Nd configuration utility for the concatenated disk driver
.Sh SYNOPSIS
.Nm
.Op Fl cv
.Ar ccd
.Ar ileave
.Op Ar flags
.Ar dev ...
.Nm
.Fl C
.Op Fl v
.Op Fl f Ar config_file
.Nm
.Fl u
.Op Fl v
.Ar ccd ...
.Nm
.Fl U
.Op Fl v
.Op Fl f Ar config_file
.Nm
.Fl g
.Op Fl M Ar core
.Op Fl N Ar system
.Op Ar ccd ...
.Sh DESCRIPTION
The
.Nm
utility is used to dynamically configure and unconfigure concatenated disk
devices, or ccds.
For more information about the ccd, see
.Xr ccd 4 .
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl c
Configure a ccd.
This is the default behavior of
.Nm .
.It Fl C
Configure all ccd devices listed in the ccd configuration file.
.It Fl f Ar config_file
When configuring or unconfiguring all devices, read the file
.Pa config_file
instead of the default
.Pa /etc/ccd.conf .
.It Fl g
Dump the current ccd configuration in a format suitable for use as the
ccd configuration file.
If no arguments are specified, every configured ccd is dumped.
Otherwise, the configuration of each listed ccd is dumped.
.It Fl M Ar core
Extract values associated with the name list from
.Pa core
instead of the default
.Pa /dev/mem .
.It Fl N Ar system
Use
.Ar system
as the kernel instead of the running kernel (as determined from
.Xr getbootfile 3 ) .
.It Fl u
Unconfigure a ccd.
.It Fl U
Unconfigure all ccd devices listed the ccd configuration file.
.It Fl v
Cause
.Nm
to be verbose.
.El
.Pp
A ccd is described on the command line and in the ccd configuration
file by the name of the ccd, the interleave factor, the ccd configuration
flags, and a list of one or more devices.
The flags may be represented as a decimal number, a hexadecimal number,
a comma-separated list of strings, or the word
.Dq none .
The flags are as follows:
.Bd -literal -offset indent
CCDF_SWAP       0x01            Interleave should be dmmax
CCDF_UNIFORM    0x02            Use uniform interleave
CCDF_MIRROR     0x04            Support mirroring
CCDF_PARITY     0x08            Support parity (not implemented yet)
.Ed
.Pp
The format in the
configuration file appears exactly as if it were entered on the command line.
Note that on the command line and in the configuration file, the
.Pa flags
argument is optional.
.Bd -literal -offset indent
#
# /etc/ccd.conf
# Configuration file for concatenated disk devices
#
.Pp
# ccd           ileave  flags   component devices
ccd0            16      none    /dev/da2s0e /dev/da3s0e
.Ed
.Pp
The component devices need to name partitions of type
.Li FS_CCD
(or
.Dq ccd
as shown by
.Xr disklabel 8 ) .
.Sh RECOVERY
An error on a ccd disk is usually unrecoverable unless you are using the
mirroring option.
But mirroring has its own perils:
It assumes that both copies of the data at any given sector are the same.
This holds true
until a write error occurs or until you replace either side of the mirror.
This is a poor-man's mirroring implementation.
It works well enough that if
you begin to get disk errors you should be able to backup the ccd disk,
replace the broken hardware, and then regenerate the ccd disk.
If you need more than this you should look into external hardware RAID
SCSI boxes, RAID controllers such as the
.Xr dpt 4
controller, or software RAID systems such as
.Xr vinum 8 .
.Sh FILES
.Bl -tag -width /etc/ccd.conf -compact
.It Pa /etc/ccd.conf
default ccd configuration file
.El
.Sh EXAMPLES
A number of
.Nm
examples are shown below.
The arguments passed to
.Nm
are exactly the same as you might place in the
.Pa /etc/ccd.conf
configuration file.
The first example creates a 4-disk stripe out of four SCSI disk partitions.
The stripe uses a 64 sector interleave.
The second example is an example of a complex stripe/mirror combination.
It reads as a two disk stripe of
.Pa da2s0e
and
.Pa da3s0e
which is mirrored to a two disk stripe of
.Pa da4s0e
and
.Pa da5s0e .
The last example is a simple mirror.
.Pa /dev/da2s0e
is mirrored with
.Pa /dev/da4s0e
and assigned to
.Pa ccd0 .
.Bd -literal -offset indent
# ccdconfig ccd0 64 none /dev/da2s0e /dev/da3s0e /dev/da4s0e \e
        /dev/da5s0e
# ccdconfig ccd0 128 CCDF_MIRROR /dev/da2s0e /dev/da3s0e \e
        /dev/da4s0e /dev/da5s0e
# ccdconfig ccd0 128 CCDF_MIRROR /dev/da2s0e /dev/da4s0e
.Ed
.Pp
When you create a new ccd disk you generally want to label it, using
.Xr disklabel 8
or
.Xr disklabel64 8 ,
before doing anything else.
Once you create the initial label you can edit it, adding additional partitions.
The label itself takes up the first 16 sectors of the ccd disk.
If all you are doing is creating file systems with
.Xr newfs 8 ,
you do not have to worry about this as
.Xr newfs 8
will skip the label area.
However, if you intend to
.Xr dd 1
to or from a ccd partition it is usually a good idea to construct the
partition such that it does not overlap the label area.
For example, if you have A ccd disk with 10000 sectors you might create a
.Ql d
partition with offset 16 and size 9984.
.Bd -literal -offset indent
# disklabel -r -w ccd0s0 auto
# disklabel -e ccd0s0
.Ed
.Pp
The disklabeling of a ccd disk is usually a one-time affair.
If you reboot the machine and reconfigure the ccd disk, the disklabel you
had created before will still be there and not require reinitialization.
Beware that changing any ccd parameters: interleave, flags, or the
device list making up the ccd disk, will usually destroy any prior
data on that ccd disk.
If this occurs it is usually a good idea to
reinitialize the label before [re]constructing your ccd disk.
.Sh SEE ALSO
.Xr dd 1 ,
.Xr ccd 4 ,
.Xr dpt 4 ,
.Xr disklabel 8 ,
.Xr disklabel64 8 ,
.Xr rc 8 ,
.Xr vinum 8
.Sh HISTORY
The
.Nm
utility first appeared in
.Nx 1.0a .