Replicate files across dissimilar networks

Many systems administrators prefer to copy master files to one or more central servers for easier access, or they distribute some system files to remote computers on their networks to reduce the amount of network load in the environment. PowerSync 4.5 Server was made for these individuals.

Very simply, PowerSync 4.5 is a file and directory replication tool that can help you easily distribute files to your users, regardless of whether you're using one OS or working in a heterogeneous environment. The software automatically replicates the contents of a directory or one or more files from one source computer to other computers on your network, unattended in the background. The product relies heavily on your company's existing networking infrastructure to transfer files. So, rather than adding another layer of software to handle file transfers, the product uses the built-in file sharing networking capabilities of Windows NT and the destination OSs to handle the file transfers.

To use PowerSync, you must have a functional network in place. So, if your source files reside on an NT server and you want to automatically transfer them to a UNIX machine, a NetWare machine, or several PC-based workstations, you must have built-in file sharing between the systems. For example, if you want to share files with a NetWare server, you can simply log on to the NetWare Server (or use the NT Gateway Service for NetWare). For a UNIX server, you need to set up some form of Common Internet File System (CIFS) software on the UNIX side (such as Samba or SCO’s VisionFS) to be able to create shares on the UNIX side that NT can access.

I set up the software on my Windows NT 4.0 Server system and used it to replicate files to several other servers on my network. The product has a Windows Explorer-like configuration tool, as Screen 1 shows, where I selected the directories and files I wanted to replicate, as well as their destination locations. However, PowerSync 4.5 Server offers more than mere file copy features. I found if I created a new file in a directory I had configured for replication, the software automatically replicated that file to the destination directory. Likewise, if I deleted a file in my source directory, the product also deleted the file on the destination computer.

PowerSync uses file timestamps to determine whether it should transfer a file to a remote system. The software examines the timestamp of the source file and compares it to the timestamp of the remote file. If the source file is newer than the destination file, the software copies the source file to the destination computer. This feature is helpful in cutting down the amount of load on my network. After you set up the initial replication process, maintaining updates on the remote computers doesn't consume much bandwidth.

One software feature that I particularly liked was its capability of performing 2-way replication. With most replication tools, replication is only 1-way. With PowerSync, the software can check both the source and destination files, determine which file is the most up to date, and transfer the most up-to-date file back to the other computer system.

The software has several other features that I found very helpful in replicating files and directories. For instance, I configured the software's email feature so that the program automatically notified me with an email message whenever it had a problem with the replication process. A "check drive mappings" option can also verify that no destination paths have been removed from the system before the software begins replicating files.

Despite these useful features, I began asking myself, "Is this all it does?" Many individuals with purchasing authority in MIS departments would agree: Why purchase this product when you can virtually accomplish the same thing using software NT already makes available to you? You can easily replicate much of what this product offers using native NT command-line batch scripts.

Unfortunately, the more I thought about the product, the more elusive an answer to my question became. This product could be of tremendous help to a company without technically savvy staff and create scripts for them, but the likelihood that such a company has the technical resources to properly maintain a functional file sharing network that the software requires is likewise unlikely.

PowerSync's cost is not significant—only $1795 for a five-server license. However, because you can easily duplicate the product’s core functions with a little script programming savvy, this product is best suited for environments where a technically oriented employee is available. A technically savvy user can set up PowerSync to run as an NT service using the Microsoft utilities srvany.exe and instsrv.exe, so you don't need to have a user logged in to run the program. In this type of environment, especially one with dissimilar network OSs, this product is an excellent solution.

PowerSync 4.5 Server
Contact: LinkPro * 949-833-3322
Web: http://www.linkpro.com
Price: $1795 (5-server license), $299 each additional server license
System Requirements: Windows NT 4.0 (Workstation or Server), 486 processor or better, 16MB of RAM, 1MB of hard disk space