GRAID3(8)

NAME
graid3 - control utility for RAID3 devices

SYNOPSIS
graid3 label [-Fhnrvw] [-s blocksize] name prov prov prov ...
graid3 clear [-v] prov ...
graid3 configure [-adfFhnrRvwW] name
graid3 rebuild [-v] name prov
graid3 insert [-hv] [-n number] name prov
graid3 remove [-v] -n number name
graid3 stop [-fv] name ...
graid3 list
graid3 status
graid3 load
graid3 unload

DESCRIPTION
The graid3 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 graid3 utility uses on-disk metadata (the provider's last sector) to store all needed information.

The first argument to graid3 indicates an action to be performed:

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).

    Additional options include:

    -F  Do not synchronize after a power failure or system crash. Assumes device is in consistent state.

    -h  Hardcode providers' names in metadata.

    -n  Turn off autosynchronization of stale components.

    -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 -w option is also specified.

    -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.

    -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 EIO error is returned and the value of the kern.geom.raid3.stat.parity_mismatch sysctl is increased. One cannot use this option if the -r option is also specified.

clear
    Clear metadata on the given providers.

configure
    Configure the given device.

    Additional options include:

    -a  Turn on autosynchronization of stale components.

    -d  Do not hardcode providers' names in metadata.

    -f  Synchronize device after a power failure or system crash.

    -F  Do not synchronize after a power failure or system crash. Assumes device is in consistent state.

    -h  Hardcode providers' names in metadata.

    -n  Turn off autosynchronization of stale components.

    -r  Turn on round-robin reading.

    -R  Turn off round-robin reading.

    -w  Turn on verify reading.

    -W  Turn off verify reading.

rebuild
    Rebuild the given component forcibly. If autosynchronization was not turned off for the given device, this command should be unnecessary.

insert
    Add the given component to the existing array, if one of the components was removed previously with the 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.

    Additional options include:

    -h  Hardcode providers' names in metadata.

remove
    Remove the given component from the given array and clear metadata on it.

stop
    Stop the given arrays.

    Additional options include:

    -f  Stop the given array even if it is opened.

list
    See geom(8).

status
    See geom(8).

load
    See geom(8).

unload
    See geom(8).

Additional options include:

-v  Be more verbose.

EXIT STATUS
Exit status is 0 on success, and 1 if the command fails.

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:

    graid3 label -v -r data da0 da1 da2
    newfs /dev/raid3/data
    mount /dev/raid3/data /mnt
    ...
    umount /mnt
    graid3 stop data
    graid3 unload

Create a RAID3 array, but do not use the automatic synchronization feature. Rebuild parity component:

    graid3 label -n data da0 da1 da2
    graid3 rebuild data da2

Replace one data disk with a brand new one:

    graid3 remove -n 0 data
    graid3 insert -n 0 data da5

SEE ALSO
geom(4), geom(8), mount(8), newfs(8), umount(8)

HISTORY
The graid3 utility appeared in FreeBSD 5.3.

AUTHORS
Pawel Jakub Dawidek <pjd@FreeBSD.org>

BUGS
There should be a section with an implementation description.

Documentation for sysctls kern.geom.raid3.* is missing.