freebsd-nq/sbin/geom/class/raid3/graid3.8

.\" Copyright (c) 2004-2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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.Dd January 15, 2012
.Dt GRAID3 8
.Os
.Sh NAME
.Nm graid3
.Nd "control utility for RAID3 devices"
.Sh SYNOPSIS
.Nm
.Cm label
.Op Fl Fhnrvw
.Op Fl s Ar blocksize
.Ar name
.Ar prov prov prov ...
.Nm
.Cm clear
.Op Fl v
.Ar prov ...
.Nm
.Cm configure
.Op Fl adfFhnrRvwW
.Ar name
.Nm
.Cm rebuild
.Op Fl v
.Ar name
.Ar prov
.Nm
.Cm insert
.Op Fl hv
.Op Fl n Ar number
.Ar name
.Ar prov
.Nm
.Cm remove
.Op Fl v
.Fl n Ar number
.Ar name
.Nm
.Cm stop
.Op Fl fv
.Ar name ...
.Nm
.Cm list
.Nm
.Cm status
.Nm
.Cm load
.Nm
.Cm unload
.Sh DESCRIPTION
The
.Nm
utility is used for RAID3 array configuration.
After a device is created, all components are detected and configured
automatically.
All operations such as failure detection, stale component detection, rebuild
of stale components, etc.\& are also done automatically.
The
.Nm
utility uses on-disk metadata (the provider's last sector) to store all needed
information.
.Pp
The first argument to
.Nm
indicates an action to be performed:
.Bl -tag -width ".Cm configure"
.It Cm label
Create a RAID3 device.
The last given component will contain parity data, whilst the others
will all contain regular data.
The number of components must be equal to 3, 5, 9, 17, etc.\& (2^n + 1).
.Pp
Additional options include:
.Bl -tag -width ".Fl h"
.It Fl F
Do not synchronize after a power failure or system crash.
Assumes device is in consistent state.
.It Fl h
Hardcode providers' names in metadata.
.It Fl n
Turn off autosynchronization of stale components.
.It Fl r
Use parity component for reading in round-robin fashion.
Without this option the parity component is not used at all for reading operations
when the device is in a complete state.
With this option specified random I/O read operations are even 40% faster,
but sequential reads are slower.
One cannot use this option if the
.Fl w
option is also specified.
.It Fl s
Manually specify array block size. Block size will be set equal to least
common multiple of all component's sector sizes and specified value.
Note that array sector size calculated as multiple of block size and number
of regular data components. Big values may decrease performance and compatibility,
as all I/O requests have to be multiple of sector size.
.It Fl w
Use verify reading feature.
When reading from a device in a complete state, also read data from the parity component
and verify the data by comparing XORed regular data with parity data.
If verification fails, an
.Er EIO
error is returned and the value of the
.Va kern.geom.raid3.stat.parity_mismatch
sysctl is increased.
One cannot use this option if the
.Fl r
option is also specified.
.El
.It Cm clear
Clear metadata on the given providers.
.It Cm configure
Configure the given device.
.Pp
Additional options include:
.Bl -tag -width ".Fl a"
.It Fl a
Turn on autosynchronization of stale components.
.It Fl d
Do not hardcode providers' names in metadata.
.It Fl f
Synchronize device after a power failure or system crash.
.It Fl F
Do not synchronize after a power failure or system crash.
Assumes device is in consistent state.
.It Fl h
Hardcode providers' names in metadata.
.It Fl n
Turn off autosynchronization of stale components.
.It Fl r
Turn on round-robin reading.
.It Fl R
Turn off round-robin reading.
.It Fl w
Turn on verify reading.
.It Fl W
Turn off verify reading.
.El
.It Cm rebuild
Rebuild the given component forcibly.
If autosynchronization was not turned off for the given device, this command
should be unnecessary.
.It Cm insert
Add the given component to the existing array, if one of the components was
removed previously with the
.Cm remove
command or if one component is missing and will not be connected again.
If no number is given, new component will be added instead of first missed
component.
.Pp
Additional options include:
.Bl -tag -width ".Fl h"
.It Fl h
Hardcode providers' names in metadata.
.El
.It Cm remove
Remove the given component from the given array and clear metadata on it.
.It Cm stop
Stop the given arrays.
.Pp
Additional options include:
.Bl -tag -width ".Fl f"
.It Fl f
Stop the given array even if it is opened.
.El
.It Cm list
See
.Xr geom 8 .
.It Cm status
See
.Xr geom 8 .
.It Cm load
See
.Xr geom 8 .
.It Cm unload
See
.Xr geom 8 .
.El
.Pp
Additional options include:
.Bl -tag -width ".Fl v"
.It Fl v
Be more verbose.
.El
.Sh EXIT STATUS
Exit status is 0 on success, and 1 if the command fails.
.Sh EXAMPLES
Use 3 disks to setup a RAID3 array (with the round-robin reading feature).
Create a file system, mount it, then unmount it and stop device:
.Bd -literal -offset indent
graid3 label -v -r data da0 da1 da2
newfs /dev/raid3/data
mount /dev/raid3/data /mnt
\&...
umount /mnt
graid3 stop data
graid3 unload
.Ed
.Pp
Create a RAID3 array, but do not use the automatic synchronization feature.
Rebuild parity component:
.Bd -literal -offset indent
graid3 label -n data da0 da1 da2
graid3 rebuild data da2
.Ed
.Pp
Replace one data disk with a brand new one:
.Bd -literal -offset indent
graid3 remove -n 0 data
graid3 insert -n 0 data da5
.Ed
.Sh SEE ALSO
.Xr geom 4 ,
.Xr geom 8 ,
.Xr gvinum 8 ,
.Xr mount 8 ,
.Xr newfs 8 ,
.Xr umount 8
.Sh HISTORY
The
.Nm
utility appeared in
.Fx 5.3 .
.Sh AUTHORS
.An Pawel Jakub Dawidek Aq Mt pjd@FreeBSD.org
.Sh BUGS
There should be a section with an implementation description.
.Pp
Documentation for sysctls
.Va kern.geom.raid3.*
is missing.