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NAMEnbdkit-blocksize-filter - nbdkit blocksize filterSYNOPSISnbdkit --filter=blocksize plugin [minblock=SIZE] [maxdata=SIZE] \ [maxlen=SIZE] [plugin-args...] DESCRIPTION"nbdkit-blocksize-filter" is a filter that ensures various block size limits are met on transactions presented to the plugin. The NBD protocol permits clients to send requests with a granularity as small as 1 byte or as large as nearly 4 gigabytes, although it suggests that portable clients should align requests to 512 bytes and not exceed 32 megabytes without prior coordination with the server.Meanwhile, some plugins require requests to be aligned to 512-byte multiples, or may enforce a maximum transaction size to bound the time or memory resources spent by any one command (note that nbdkit itself refuses a read or write larger than 64 megabytes, while many other NBD servers limit things to 32 megabytes). The blocksize filter can be used to modify the client requests to meet the plugin restrictions. PARAMETERSThe nbdkit-blocksize-filter accepts the following parameters.
EXAMPLESAllow an arbitrary client to use the VDDK plugin (which is limited to 512-byte blocks), without having to fix the client to avoid sending unaligned requests:nbdkit --filter=blocksize vddk minblock=512 file=/absolute/path/to/file.vmdk Allow an arbitrary client tuned to nbdkit's 64 megabyte sizing to connect to a remote server that insists on 32 megabyte sizing, via the nbd plugin: nbdkit --filter=blocksize nbd maxdata=32M socket=/path/to/socket Serve a file as if it were a block device that insists on 4k alignment, while still allowing access to any unaligned bytes at the end of the file: nbdkit --filter=blocksize --filter=truncate file /path/to/file \ minblock=4k round-up=4k FILES
VERSION"nbdkit-blocksize-filter" first appeared in nbdkit 1.4.SEE ALSOnbdkit(1), nbdkit-nbd-plugin(1), nbdkit-vddk-plugin(1), nbdkit-filter(3), nbdkit-truncate-filter(1).AUTHORSEric BlakeCOPYRIGHTCopyright (C) 2018 Red Hat Inc.LICENSERedistribution 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.
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