Synchronizing Resources without Clustering
As networks grow more complex, it is easy for IT departments to lose sight of the mundane, yet vital, operation of synchronizing information resources. One tool that can help keep a handle on this process is SureSync Real-Time from Software Pursuits Inc.
We installed the product into a two-server network running Windows NT Server 4.0 with Service Pack 4 installed. For our test, we used the package to synchronize file sets between the servers for a Web-based time keeping application and for other critical files.
There are three primary components to SureSync Real-Time. A scheduler process and a file synchronization process form the base SureSync product; the Real-Time extensions add a monitoring process to the mix. All components were automatically installed, though not immediately configured, during the CD-ROM installation.
The scheduler and file synchronization components can run as applications on any Windows NT or Windows 9x system, or as services on Windows NT. The monitor process runs as a service only on NT systems.
Once installed, a graphical management utility uses familiar tree-structured displays when configuring the product. The configuration information is kept in a Microsoft Access database, which can reside on the server or another workstation. Access to the configuration database may present a security concern in some environments, which is disclosed in the documentation.
For instance, rules defined in the database may be run at a higher priority level than that of the user who entered the rules, making it possible to copy files from secure locations to unsecured locations. The manual did offer suggestions about how to use Microsoft Access and operating system security features to limit access rights.
The product documents offered examples of different possible configurations, but we were disappointed that the examples weren’t accompanied by more explicit configuration steps to build and support each scenario. In our case, we did a "server installation" to our domain controller, and then ran the setup program to install the software to run from that server. The setup needed to be run on both the domain controller itself and the secondary, member server.
For control of file-copying behavior, the product centers on defining a relationship. Each relationship lists two or more root file storage areas, then defines the rules by which files can be moved or copied among the storage areas. A relationship may have any number of rules associated with it. For example, a publicly shared directory might have different rules for word processing documents than those for spreadsheets. Each relationship can be given a priority -- low, medium or high -- to control how urgently it is processed. Custom priorities also can be defined.
The user can choose from among nine types of rules, including three kinds of master-slave relationships, exchanging of copies and two kinds of mirroring. Once a rule is selected, the user can define masks for file selections, date parameters and a wide array of criteria for choosing which files and attributes are moved or copied and to where.
One excellent feature of the product is the preview mode, where the administrator can see in advance the effect of a chosen relationship and it’s rules. The only serious limitation of the preview is that it cannot accurately portray what could happen when overlapping relationships are processed. The manual carefully explains this and suggests that the preview mode be used to process one relationship at a time.
After each relationship is defined and its rules set up, the next step is to establish one or more schedules. Each schedule associates a set of one or more relationships with the dates and times on which those relationships should be processed. Thus, high-importance files might be processed every half hour, while less-critical files might be processed once per day.
The Real-Time component adds a monitoring process, which takes the place of the schedules, that is defined manually using the base product. Rather than run at specific times to examine defined files, the monitor watches those files constantly and acts on changes it observes.
To accomplish this real-time monitoring, the monitor and scheduler processes run as a service on one or more systems in the network. Communication among the systems uses Microsoft Corp.’s Distributed Component Object Model (DCOM) technology, which allows application on one system to start and use applications and services on another. It was here that we hit a couple snags when using the product.
DCOM can be tricky to configure, and the SureSync product requires the administrator to do this manually. In our two-system network it was an unpleasant task, and it would likely be quite difficult in a typical corporate network. Also, the components -- whether under the regular NT services or the DCOM configuration -- must be run using an administrative level user account, rather than the NT system accounts. This could cause a significant headache if the account and password needed to be changed, perhaps because of a security breach.
The product also exposes a small but nasty bug in NT itself. Using a real account to start services in this manner can prevent NT from processing entries in the startup folder when a user logs on. In our test environment, users that logged onto one of the systems were without their expected menu bars and other common utilities. Software Pursuits plans to release an updated version in late October or early November that uses the NT system account to start and run the services.
SureSync Real-Time is more than an extension to the type of copying users have been doing by hand for years. Its rules-based, unattended processing is powerful, but power can be dangerous when used unwisely. We found SureSync Real-Time to be relatively easy to handle, and the flexibility of its rules and the unobtrusive nature of its background processing were attractive. On the other hand, the finicky nature of DCOM and the potential for problems with both security and user functionality should prompt administrators to deploy the product carefully.
Software Pursuits Inc.
San Mateo, Calif.
Price: Two server license, $1,800; additional server, $900; workstation, $149. Volume pricing is available
+ Flexible rules
+ Moderate size
-DCOM real-time configuration capabilities is tricky
-Security concerns with controlling access