nbdkit-qcow2dec-filter(1)

1nbdkit-qcow2dec-filter(1)           NBDKIT           nbdkit-qcow2dec-filter(1)
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NAME

6       nbdkit-qcow2dec-filter - decode qcow2 files
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SYNOPSIS

9        nbdkit --filter=qcow2dec PLUGIN
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DESCRIPTION

12       "nbdkit-qcow2dec-filter" is a filter for nbdkit(1) that can decode some
13       qcow2 files.  You can use it on top of plugins that provide qcow2 data,
14       such as nbdkit-file-plugin(1) or nbdkit-curl-plugin(1).  For example to
15       expose a local qcow2 file as raw format over NBD:
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17        nbdkit -r --filter=qcow2dec file image.qcow2
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19       This filter can only decode qcow2 files, it cannot write to them, and
20       it has other limitations.  See "LIMITATIONS" below.  The NBD export
21       will be read-only unless you use nbdkit-cow-filter(1) on top.
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23       qemu-nbd(8) is an alternate NBD server with native support for qcow2.
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LIMITATIONS

26       This filter has several limitations, and some of them we never intend
27       to implement.  For general qcow2 access, especially creating and
28       writing to qcow2 files, it is always better to use qemu and tools such
29       as qemu-img(1) and qemu-nbd(8).
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31       Read-only
32           This filter only supports decoding qcow2 into raw format.  You
33           cannot write to the qcow2 file.  The NBD export will be read-only.
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35       Versions 2 and 3 only
36           Only qcow2 subversions 2 and 3 (a.k.a. "compat=0.10" and
37           "compat=1.1") are supported.
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39       Deflate or Zstd compression only
40           The most common types of qcow2 compression are supported if nbdkit
41           was built with the correct libraries.  To find out which types of
42           compression are supported, use:
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44            $ nbdkit null --filter=qcow2dec --dump-plugin
45            ...
46            qcow2dec_deflate=yes       # printed if Deflate (zlib) is supported
47            qcow2dec_zstd=yes          # printed if Zstd is supported
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49       No snapshots
50           We may add the ability to extract an internal snapshot in future.
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52       No bitmaps
53           It may be possible to support bitmaps in future.
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55       No backing files
56       No dirty or corrupted qcow2 files
57       No encryption
58       No extended L2 entries
59       No external data files
60           These features are not currently supported and unlikely to be
61           supported in future.
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PARAMETERS

64       There are no parameters specific to this filter.  Parameters are passed
65       through to the underlying plugin.
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FILES

68       $filterdir/nbdkit-qcow2dec-filter.so
69           The filter.
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71           Use "nbdkit --dump-config" to find the location of $filterdir.
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VERSION

74       "nbdkit-qcow2dec-filter" first appeared in nbdkit 1.36.
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AUTHORS

84       Richard W.M. Jones
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COPYRIGHT

87       Copyright Red Hat
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LICENSE

90       Redistribution and use in source and binary forms, with or without
91       modification, are permitted provided that the following conditions are
92       met:
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94       •   Redistributions of source code must retain the above copyright
95           notice, this list of conditions and the following disclaimer.
96
97       •   Redistributions in binary form must reproduce the above copyright
98           notice, this list of conditions and the following disclaimer in the
99           documentation and/or other materials provided with the
100           distribution.
101
102       •   Neither the name of Red Hat nor the names of its contributors may
103           be used to endorse or promote products derived from this software
104           without specific prior written permission.
105
106       THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY
107       EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
108       IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
109       PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE
110       LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
111       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
112       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
113       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
114       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
115       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
116       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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120nbdkit-1.36.2                     2023-11-26         nbdkit-qcow2dec-filter(1)