FTP servers and SyncBackSE

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FTP servers and SyncBackSE

Post by mickyj » Thu Feb 24, 2005 8:55 am

Listed below are the features that an ideal FTP server should support:


These commands are used to set the last modification date & time of a file. If the FTP server supports MFMT or SITE UTIME then that is ideal. However, some older or less capable FTP server do not support MFMT or SITE UTIME, but may support the MDTM command.

The MDTM command has two functions: to get the last modification date & time of a file, and to set the last modification date & time of a file. Most servers support getting the date & time, but some do not support setting the date & time.

If the FTP server does not support setting a files date & time via MFMT, SITE UTIME, or MDTM then SyncBackSE has two options: to change the local files date & time to match that of the file on the FTP server (the default), or to record the date & time of the local file in the Fast Backup results (you must enable Fast Backup and disable the option "Force the file modification date & time to be correct" on the Copy/Delete tab).


This command is used to retrieve the details of all files and directories within a directory on the FTP server. If a server supports this command then SyncBackSE can scan the server considerably faster. If the server does not support this command then SyncBackSE must make two extra calls per file to the server. For example, if a server supports MLSD then only one call to the server is required per directory, but if it doesn't support MLSD then there will be one call to get the list of files and sub-directories, followed by two calls per file in that directory.


A few servers support MODE Z compression. This allows files to be sent to and retrieved from the server in compressed format. For high bandwidth connections it's generally not necessary to use MODE Z compression. Also note that some servers may support MODE Z compression but the administrators of that server may have disabled it (as it uses more CPU time and so could overload the server).


Some servers support SSL/TLS encryption (implicit and/or explicit). If the server does support it then SyncBackSE can securely send and receive files to and from the server. Note that encryption does impact performance and so should only be used if required. SyncBackPro (not SyncBackSE) also supports SFTP servers, which provide encrypted connections.


FTP is a text protocol, not binary. Therefore it can have problems with some filenames, e.g. Chinese. To get around this problem some FTP servers accept filenames in UTF-8. UTF-8 is an ASCII-preserving encoding method for Unicode (ISO 10646), the Universal Character Set (UCS). Please note that even though some FTP servers claim to support UTF8, their implementation of it is either broken or partially working.


If the server supports the XCRC extension then SyncBackSE can verify that files transferred to or from the server have been transmitted correctly, i.e. the file on the FTP server is the same as the local file based on its CRC value.