nbdkit-map-filter - remap disk blocks
nbdkit --filter=map PLUGIN [map=START-END:DEST [map=...]]
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.
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
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)).
The filter.
Use nbdkit --dump-config
to find the location of $filterdir
.
nbdkit-map-filter
first appeared in nbdkit 1.46.
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).
Richard W.M. Jones
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