Como funciona a opção --fuzzy para o rsync?

Question

Como o rsync --fuzzy funciona? Eu não obtenho os resultados que espero.

Do manual:

This option tells rsync that it should look for a basis file for any destination file that is missing. The current algorithm looks in the same directory as the destination file for either a file that has an identical size and modified-time, or a similarly-named file. If found, rsync uses the fuzzy basis file to try to speed up the transfer.

If the option is repeated, the fuzzy scan will also be done in any matching alternate destination directories that are specified via --compare-dest, --copy-dest, or --link-dest.

Note that the use of the --delete option might get rid of any potential fuzzy-match files, so either use --delete-after or specify some filename exclusions if you need to prevent this.

Assim, espero que o seguinte script de shell renomeie o arquivo destination / a1 para destination / a2 na segunda execução de rsync. No entanto, como eu interpreto a saída, isso não é o que está acontecendo ( Matched data: 0 bytes ).

#! /usr/bin/env bash
set -e

cd $(mktemp -d)
mkdir source destination
cat /dev/urandom | head --bytes=1M > source/a1
rsync --recursive --times $(pwd)/source/ $(pwd)/destination/
tree
mv source/a1 source/a2
rsync \
    --verbose \
    --recursive \
    --times \
    --delete \
    --delete-after \
    --fuzzy \
    --human-readable \
    --itemize-changes \
    --stats \
    $(pwd)/source/ \
    $(pwd)/destination/
tree
rm -r source destination

Saída:

├── destination
│   └── a1
└── source
    └── a1

2 directories, 2 files
building file list ... done
>f+++++++++ a2
*deleting   a1

Number of files: 2 (reg: 1, dir: 1)
Number of created files: 1 (reg: 1)
Number of deleted files: 1 (reg: 1)
Number of regular files transferred: 1
Total file size: 1.05M bytes
Total transferred file size: 1.05M bytes
Literal data: 1.05M bytes
Matched data: 0 bytes
File list size: 0
File list generation time: 0.001 seconds
File list transfer time: 0.000 seconds
Total bytes sent: 1.05M
Total bytes received: 34

sent 1.05M bytes  received 34 bytes  2.10M bytes/sec
total size is 1.05M  speedup is 1.00
.
├── destination
│   └── a2
└── source
    └── a2

2 directories, 2 files

Saída de rsync --version :

rsync  version 3.1.2  protocol version 31
Copyright (C) 1996-2015 by Andrew Tridgell, Wayne Davison, and others.
Web site: http://rsync.samba.org/
Capabilities:
    64-bit files, 64-bit inums, 64-bit timestamps, 64-bit long ints,
    socketpairs, hardlinks, symlinks, IPv6, batchfiles, inplace,
    append, ACLs, xattrs, iconv, symtimes, prealloc

rsync comes with ABSOLUTELY NO WARRANTY.  This is free software, and you
are welcome to redistribute it under certain conditions.  See the GNU
General Public Licence for details.

Como o rsync --fuzzy funciona?

Por que não recebo os resultados esperados?

    

Answer 1

Você está usando rsync para copiar arquivos entre duas árvores de arquivos locais. O algoritmo incremental e todas as otimizações associadas, como --fuzzy , são ignoradas neste modo.

Repita o teste com um arquivo local sendo copiado para um servidor remoto (ou remoto para local; não importa) e você verá que funciona conforme o esperado.

Como exemplo, modifique seu script nos dois lugares, como $(pwd)/destination é alterado para localhost:$(pwd)/destination . Não é elegante, mas será suficiente.

# Set up PKI for localhost
ssh-keygen -t rsa
cat ~/.ssh/id_rsa.pub >>~/.ssh/authorized_keys
ssh localhost id

Resultados de script do segundo rsync :

building file list ... done
<f+++++++++ a2
*deleting   a1

Number of files: 2 (reg: 1, dir: 1)
Number of created files: 1 (reg: 1)
Number of deleted files: 1 (reg: 1)
Number of regular files transferred: 1
Total file size: 1.05M bytes
Total transferred file size: 1.05M bytes
Literal data: 0 bytes
Matched data: 1.05M bytes
File list size: 0
File list generation time: 0.001 seconds
File list transfer time: 0.000 seconds
Total bytes sent: 4.20K
Total bytes received: 6.18K

sent 4.20K bytes  received 6.18K bytes  20.75K bytes/sec
total size is 1.05M  speedup is 101.09