NAME

nbdkit-map-filter - remap disk blocks

SYNOPSIS

 nbdkit --filter=map PLUGIN [map=START-END:DEST [map=...]]

DESCRIPTION

nbdkit-map-filter is an nbdkit(1) filter which can remap parts of the underlying plugin, such as moving a sector or partition. To select part of a disk, use nbdkit-offset-filter(1) instead. To select a partition, use nbdkit-partition-filter(1). This filter cannot change the size of the disk, use nbdkit-truncate-filter(1) to do that.

EXAMPLES

Swap over the first two sectors in a disk

Using two map parameters, this remaps the first sector (bytes 0-511) on to the second sector (starting at 512), and the second sector (bytes 512-1023) on to the first sector (0).

 nbdkit --filter=map file orig.img map=0-511:512 map=512-1023:0

PARAMETERS

map=START-END:DEST

Map bytes in the range START to END (inclusive) to DEST in the underlying plugin. The destination range ends at:

 DEST_END = DEST+END-START

This means that when the byte at offset START is read or written (or any other operation such as trim), the request is redirected to the byte at offset DEST in the underlying plugin, and so on for the following bytes up to and including offset END which is mapped to DEST_END.

DEST through to DEST_END must exist in the underlying plugin. Attempts to map requests beyond the end of the underlying plugin will return I/O errors.

You can give this parameter multiple times. If overlapping ranges are described then the first matching range on the command line takes precedence. There is an implicit 1-1 mapping covering parts of the disk not covered by explicit map parameters.

If you have a large number of mappings, consider using the nbdkit @PATH parameter to read them from an external file (see "@PATH" in nbdkit(1)).

FILES

$filterdir/nbdkit-map-filter.so

The filter.

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

VERSION

nbdkit-map-filter first appeared in nbdkit 1.46.

SEE ALSO

nbdkit(1), nbdkit-extentlist-filter(1), nbdkit-offset-filter(1), nbdkit-partition-filter(1), nbdkit-protect-filter(1), nbdkit-truncate-filter(1), nbdkit-filter(3).

AUTHORS

Richard W.M. Jones

COPYRIGHT

Copyright Red Hat

LICENSE

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

THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.