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Synchronize FTP Server Wizard

Last Update: January 13, 2012

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Introduction

Portlock Storage Manager Client includes the ability to synchronize a remote FTP server with a local directory. The synchronization can be a upload (push) or a download (pull). Portlock uses this feature daily to synchronize our multiple Web and FTP servers.

Files are compared on both the local file system and the remote FTP server and missing or different files are then either uploaded or downloaded depending on the synchronization direction.

Files are compared using file size, last modified date and either MD5 or CRC32 hash algorithms. File and directory dates are also synchronized.


Required FTP Commands

File synchronization requires that the remote FTP server support the following commands:

MLSD This command provides detailed directory listings with accurate file time information.
MFMT This command provides the ability to change a file's date and time.
MDTM This command provides the ability to change a file's date and time. This command is only used if the MFMT is not supported.
XMD5 The command provides the hash of a file's contents. The file hash is used to accurately determine if files are the same.
XCRC32 The command provides the hash of a file's contents. The file hash is used to accurately determine if files are the same. This command is only used if XMD5 is not supported.

If the remote FTP server does not support the required commands, the wizard will display an error message. Portlock Storage Manager Client's built-in FTP servers supports each of these commands.


File Comparison

To determine if a file is the same, the following checks are performed:

  • If the file dates are the same and the file sizes are the same, assume that the files are the same.
  • If the file sizes are different, replace the file.
  • If the file dates are different, check the hash value of the file contents.
  • If the hash values are different replace the file.
  • If the hash values are the same then the file on both sides is the same.
  • The XMD5 command will be used if the remote ftp server supports XMD5 otherwize the XCRC comand will be used.
  • When a file is replaced, the target file's last modified date and time is set to the source file's date and time.


How to start the command

To start the Synchronize FTP Server Wizard, right-click on the FTP Server tab or select Services from the menu bar -> FTP Server -> Synchronize FTP Server.


Wizard

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