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man/orig/gmirror(8)

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grmirror • man/grmirror • man/orig/grmirror • Пример использования grmirror


GMIRROR(8) FreeBSD System Manager's Manual GMIRROR(8)

Содержание

[править] NAME

    gmirror — control utility for mirrored devices

[править] SYNOPSIS

    gmirror label [-Fhnv] [-b balance] [-s slice] name prov ...
    gmirror clear [-v] prov ...
    gmirror configure [-adfFhnv] [-b balance] [-s slice] name
    gmirror configure [-v] -p priority name prov
    gmirror rebuild [-v] name prov ...
    gmirror resize [-v] [-s size] name
    gmirror insert [-hiv] [-p priority] name prov ...
    gmirror remove [-v] name prov ...
    gmirror activate [-v] name prov ...
    gmirror deactivate [-v] name prov ...
    gmirror destroy [-fv] name ...
    gmirror forget [-v] name ...
    gmirror stop [-fv] name ...
    gmirror dump prov ...
    gmirror list
    gmirror status
    gmirror load
    gmirror unload

[править] DESCRIPTION

    The gmirror utility is used for mirror (RAID1) configurations.  After a
    mirror's creation, all components are detected and configured automati‐
    cally.  All operations like failure detection, stale component detection,
    rebuild of stale components, etc. are also done automatically.  The
    gmirror utility uses on-disk metadata (stored in the provider's last sec‐
    tor) to store all needed information.  Since the last sector is used for
    this purpose, it is possible to place a root file system on a mirror.
    The first argument to gmirror indicates an action to be performed:
    label       Create a mirror.  The order of components is important,
                because a component's priority is based on its position
                (starting from 0 to 255).  The component with the biggest
                priority is used by the prefer balance algorithm and is also
                used as a master component when resynchronization is needed,
                e.g. after a power failure when the device was open for writ‐
                ing.
                Additional options include:
                -b balance  Specifies balance algorithm to use, one of:
                            load         Read from the component with the
                                         lowest load.  This is the default
                                         balance algorithm.
                            prefer       Read from the component with the
                                         biggest priority.
                            round-robin  Use round-robin algorithm when
                                         choosing component to read.
                            split        Split read requests, which are big‐
                                         ger than or equal to slice size on N
                                         pieces, where N is the number of
                                         active components.
                -F          Do not synchronize after a power failure or sys‐
                            tem crash.  Assumes device is in consistent
                            state.
                -h          Hardcode providers' names in metadata.
                -n          Turn off autosynchronization of stale components.
                -s slice    When using the split balance algorithm and an I/O
                            READ request is bigger than or equal to this
                            value, the I/O request will be split into N
                            pieces, where N is the number of active compo‐
                            nents.  Defaults to 4096 bytes.
    clear       Clear metadata on the given providers.
    configure   Configure the given device.
                Additional options include:
                -a           Turn on autosynchronization of stale components.
                -b balance   Specifies balance algorithm to use.
                -d           Do not hardcode providers' names in metadata.
                -f           Synchronize device after a power failure or sys‐
                             tem crash.
                -F           Do not synchronize after a power failure or sys‐
                             tem crash.  Assumes device is in consistent
                             state.
                -h           Hardcode providers' names in metadata.
                -n           Turn off autosynchronization of stale compo‐
                             nents.
                -p priority  Specifies priority for the given component prov.
                -s slice     Specifies slice size for split balance algo‐
                             rithm.
    rebuild     Rebuild the given mirror components forcibly.  If autosyn‐
                chronization was not turned off for the given device, this
                command should be unnecessary.
    resize      Change the size of the given mirror.
                Additional options include:
                -s size  New size of the mirror is expressed in logical block
                         numbers.  This option can be omitted, then it will
                         be automatically calculated to maximum available
                         size.
    insert      Add the given component(s) to the existing mirror.
                Additional options include:
                -h           Hardcode providers' names in metadata.
                -i           Mark component(s) as inactive immediately after
                             insertion.
                -p priority  Specifies priority of the given component(s).
    remove      Remove the given component(s) from the mirror and clear meta‐
                data on it.
    activate    Activate the given component(s), which were marked as inac‐
                tive before.
    deactivate  Mark the given component(s) as inactive, so it will not be
                automatically connected to the mirror.
    destroy     Stop the given mirror and clear metadata on all its compo‐
                nents.
                Additional options include:
                -f  Stop the given mirror even if it is opened.
    forget      Forget about components which are not connected.  This com‐
                mand is useful when a disk has failed and cannot be recon‐
                nected, preventing the remove command from being used to
                remove it.
    stop        Stop the given mirror.
                Additional options include:
                -f  Stop the given mirror even if it is opened.
    dump        Dump metadata stored on the given providers.
    list        See geom(8).
    status      See geom(8).
    load        See geom(8).
    unload      See geom(8).
    Additional options include:
    -v  Be more verbose.

[править] EXIT STATUS

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

[править] EXAMPLES

    Use 3 disks to setup a mirror.  Choose split balance algorithm, split
    only requests which are bigger than or equal to 2kB.  Create file system,
    mount it, then unmount it and stop device:
          gmirror label -v -b split -s 2048 data da0 da1 da2
          newfs /dev/mirror/data
          mount /dev/mirror/data /mnt
          ...
          umount /mnt
          gmirror stop data
          gmirror unload
    Create a mirror on disk with valid data (note that the last sector of the
    disk will be overwritten).  Add another disk to this mirror, so it will
    be synchronized with existing disk:
          gmirror label -v -b round-robin data da0
          gmirror insert data da1
    Create a mirror, but do not use automatic synchronization feature.  Add
    another disk and rebuild it:
          gmirror label -v -n -b load data da0 da1
          gmirror insert data da2
          gmirror rebuild data da2
    One disk failed.  Replace it with a brand new one:
          gmirror forget data
          gmirror insert data da1
    Create a mirror, deactivate one component, do the backup and connect it
    again.  It will not be resynchronized, if there is no need to do so
    (there were no writes in the meantime):
          gmirror label data da0 da1
          gmirror deactivate data da1
          dd if=/dev/da1 of=/backup/data.img bs=1m
          gmirror activate data da1

[править] NOTES

    Doing kernel dumps to gmirror providers.
    This is possible, but some conditions have to be met.  First of all, a
    kernel dump will go only to one component and gmirror always chooses the
    component with the highest priority.  Reading a dump from the mirror on
    boot will only work if the prefer balance algorithm is used (that way
    gmirror will read only from the component with the highest priority).  If
    you use a different balance algorithm, you should add:
          gmirror configure -b prefer data
    to the /etc/rc.early script and:
          gmirror configure -b round-robin data
    to the /etc/rc.local script.  The decision which component to choose for
    dumping is made when dumpon(8) is called.  If on the next boot a compo‐
    nent with a higher priority will be available, the prefer algorithm will
    choose to read from it and savecore(8) will find nothing.  If on the next
    boot a component with the highest priority will be synchronized, the pre‐
    fer balance algorithm will read from the next one, thus will find nothing
    there.

[править] SEE ALSO


[править] HISTORY

    The gmirror utility appeared in FreeBSD 5.3.

[править] AUTHORS

    Pawel Jakub Dawidek <pjd@FreeBSD.org>

[править] BUGS

    There should be a way to change a component's priority inside a running
    mirror.
    There should be a section with an implementation description.
    Documentation for sysctls kern.geom.mirror.* is missing.

FreeBSD 10.1 December 27, 2013 FreeBSD 10.1