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gjournal (8)
  • >> gjournal (8) ( FreeBSD man: Команды системного администрирования )

  • BSD mandoc
     

    NAME

    
    
    gjournal
    
     - control utility for journaled devices
    
     
    

    SYNOPSIS

    label [-cfhv ] [-s jsize ] dataprov [jprov ]
    stop [-fv ] name ...
    sync [-v ]
    clear [-v ] prov ...
    dump prov ...
    list
    status
    load
    unload  

    DESCRIPTION

    The utility is used for journal configuration on the given GEOM provider. The Journal and data may be stored on the same provider or on two separate providers. This is block level journaling, not file system level journaling, which means everything gets logged, e.g. for file systems, it journals both data and metadata. The GEOM class can talk to file systems, which allows the use of for file system journaling and to keep file systems in a consistent state. At this time, only UFS file system is supported.

    To configure journaling on the UFS file system using , one should first create a provider using the utility, then run newfs(8) or tunefs(8) on it with the -J flag which instructs UFS to cooperate with the provider below. There are important differences in how journaled UFS works. The most important one is that sync(2) and fsync(2) system calls do not work as expected anymore. To ensure that data is stored on the data provider, the sync command should be used after calling sync(2). For the best performance possible, soft-updates should be disabled when is used. It is also safe and recommended to use the async mount(8) option.

    When is configured on top of gmirror(8) or graid3(8) providers, it also keeps them in a consistent state, thus automatic synchronization on power failure or system crash may be disabled on those providers.

    The utility uses on-disk metadata, stored in the provider's last sector, to store all needed information. This could be a problem when an existing file system is converted to use .

    The first argument to indicates an action to be performed:

    label
    Configures on the given provider(s). If only one provider is given, both data and journal are stored on the same provider. If two providers are given, the first one will be used as data provider and the second will be used as the journal provider.

    Additional options include:

    -c
    Checksum journal records.
    -f
    May be used to convert an existing file system to use , but only if the journal will be configured on a separate provider and if the last sector in the data provider is not used by the existing file system. If detects that the last sector is used, it will refuse to overwrite it and return an error. This behavior may be forced by using the -f flag, which will force to overwrite the last sector.
    -h
    Hardcode provider names in metadata.
    -s jsize
    Specifies size of the journal if only one provider is used for both data and journal. The default is one gigabyte. Size should be chosen based on provider's load, and not on its size. It is not recommended to use for small file systems (e.g.: only few gigabytes big).

    clear
    Clear metadata on the given providers.
    stop
    Stop the given provider.

    Additional options include:

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

    sync
    Trigger journal switch and enforce sending data to the data provider.
    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.

     

    EXIT STATUS

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

    EXAMPLES

    Create a based UFS file system and mount it:
    gjournal load
    gjournal label da0
    newfs -J /dev/da0.journal
    mount -o async /dev/da0.journal /mnt
    

    Configure journaling on an existing file system, but only if allows this (i.e., if the last sector is not already used by the file system):

    umount /dev/da0s1d
    gjournal label da0s1d da0s1e && \
        tunefs -J enable -n disable da01sd.journal && \
        mount -o async /dev/da0s1d.journal /mnt || \
        mount /dev/da0s1d /mnt
    
     

    SEE ALSO

    geom(4), geom(8), mount(8), newfs(8), tunefs(8), umount(8)  

    HISTORY

    The utility appeared in Fx 7.0 .  

    AUTHORS

    An Pawel Jakub Dawidek Aq [email protected]  

    BUGS

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


     

    Index

    NAME
    SYNOPSIS
    DESCRIPTION
    EXIT STATUS
    EXAMPLES
    SEE ALSO
    HISTORY
    AUTHORS
    BUGS


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