File synchronization

This chapter contains

Creating or editing a configuration

File synchronization example screenshot

The marked items in the figure are explained below:

  1. Current configuration name

    If you’re creating a new configuration, this will be called “<untitled>” or similar. But in case you’re editing an existing configuration, its name will be displayed on the tab.

  2. Define a configuration name

    This is a friendly name that you define for the synchronization configuration. For example, you could name it “Backup documents to external hard drive”.

  3. Local folder

    When running a file synchronization configuration, DogSync checks for differences between two folders and lets you decide which actions to take. The local folder must be chosen on the computer on which DogSync is running. Therefore, click on the folder selection button and choose “Other...”. Then, open the desired source folder and confirm. Mind that this is a GTK dialog which can be a bit impractical sometimes - make sure the correct directory is selected by looking at the resource URI that DogSync created in the text entry left of the folder selection button.

    Note

    If you are using Windows, you will note that a special path URL is created. Something like file_windows_volumeid://[1839328602]\Music, for example. The number is the unique identifier that Windows provides for each file system that is natively supported on Windows (at least for NTFS as far as I know). This allows DogSync to detect whether a drive letter is suddenly connected to a different drive. If you don’t know what this means you can simply ignore it.

  4. Remote folder

    The remote folder can either be a directory on the local computer or on another computer that is running DogSync, too. As long as you don’t run the synchronization, DogSync does not need to be running on the remote computer.

    So far, remote resources can be specified by the IPv4 network address or hostname, and by the absolute path to the remote directory. In order to specify the remote directory, click on the “Select...” button.

  5. Rename detection

    DogSync offers automatic detection of renames. All files that are identical on the local and remote side, and are larger or as large as the specified size, are considered as renamed. The threshold size can be specified in the configuration. Setting a too small size will detect renames of files that have the same content but aren’t logically “the same”.

  6. File content comparison using checksums

    You can define which hash algorithm to use when creating checksums on files for local and remote files. If you don’t use checksums (first option), rename detection will not work and DogSync can only compare files based on the filename, size and modification time, for example. This is not implemented yet, so if you disable checksums, files are only compared based on the filename and size.

    Different hash algorithms can be chosen for small and large files. For instance, this makes sense if you must be absolutely sure that small files are fully identical. The default algorithm, Dog File Hash (DFH), only reads parts of a file when creating a checksum (for a certain size, it always reads the same parts). It was designed be fast but still good in finding differences. But if changes are made to a part of a file that will not get measured by DFH, it will not be recognized as a modified file. For that reason, DogSync will later implement more “common” algorithms that calculate a checksum of the whole file. Obviously, this will be a lot slower for very large files. And large files don’t change as often as small files.

    For instance, you often edit documents of about several hundred kilobytes but you would never edit a large ISO image. In this case, you can configure DogSync to create a full checksum for each small file (like documents) but a sparse checksum for large files (e.g. ISO images). This way, you combine the speed of DFH for large files with the detection of all changes in small files.

  7. Threshold for large files

    Files that are larger or as large as defined here are considered as large files and thus DogSync applies the checksum algorithms that you chose for large files.

  8. Don’t forget to save

    With the save/cancel buttons, you can confirm or discard the changes you made to the configuration. As long as the configuration tab is open, you cannot run the synchronization.

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