Compression

Certain data types, such as text documents, may transfer faster if the data is compressed while in transit.  ExpeDat versions 1.9 and later offer inline ZLIB compression, which typically reduces the size of compressible data types to about one-third of their original size.

Compression is activated in movedat by using the -z command line option.  For example:

movedat -z user@foo.bar.com:/path/downloadme /local/destination

Compression should only be used on files known to contain compressible data, such as text documents.  For these data types, compression may increase transfer speeds by three times or more, on top of MTP's throughput gains.

Compression is very CPU intensive.  Data files which are already compressed, encoded, or encrypted, will not benefit from compression.  If the server or client is CPU limited, enabling compression may severely reduce performance.  If you are on a very fast network, even compressible data may move faster without compression due to the CPU overhead of compressing it.  See DEI Technical Note 0014 for tips on deciding when to enable compression.

The best way to tell whether a given file type will benefit from compression when transferring to a given server is to experiment with the setting both on and off to see which is faster.

Older servers and servers where compression is disabled will return an error if you attempt a compressed transaction.

For additional methods of compression and multi-file packaging, refer to the section "Getting Packages".  Note that you cannot combine inline compression with external packaging: you may only use one or the other.