NAME

       nbdkit-noextents-filter - disable extents in the underlying plugin

SYNOPSIS

        nbdkit --filter=noextents plugin

DESCRIPTION

       “Extents” are a feature of the NBD protocol / nbdkit which allow the client to detect sparse regions of
       the underlying disk.  "nbdkit-noextents-filter" disables this so that the plugin appears to be fully
       allocated, at least to a client that requests structured replies.  It is also possible to use the --no-sr
       option to nbdkit to prevent the client from using structured replies, which among its other side effects
       will prevent the client from querying extents at all.

       This filter can be useful when combined with nbdkit-file-plugin(1) serving a file from a file system
       known to have poor lseek(2) performance ("tmpfs" is known to be one such system).

PARAMETERS

       There are no parameters specific to nbdkit-noextents-filter.  Any parameters are passed through to and
       processed by the underlying plugin in the normal way.

FILES

       $filterdir/nbdkit-noextents-filter.so
           The filter.

           Use "nbdkit --dump-config" to find the location of $filterdir.

VERSION

       "nbdkit-noextents-filter" first appeared in nbdkit 1.14.

SEE ALSO

       nbdkit(1), nbdkit-filter(3), nbdkit-fua-filter(1), nbdkit-nocache-filter(1), nbdkit-noparallel-filter(1),
       nbdkit-nozero-filter(1), nbdkit-file-plugin(1).

AUTHORS

       Richard W.M. Jones

COPYRIGHT

       Copyright (C) 2019 Red Hat Inc.

LICENSE

       Redistribution and use in source and binary forms, with or without modification, are permitted provided
       that the following conditions are met:

       •   Redistributions of source code must retain the above copyright notice, this list of conditions and
           the following disclaimer.

       •   Redistributions in binary form must reproduce the above copyright notice, this list of conditions and
           the following disclaimer in the documentation and/or other materials provided with the distribution.

       •   Neither the name of Red Hat nor the names of its contributors may be used to endorse or promote
           products derived from this software without specific prior written permission.

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