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By Christopher Little M odern SCADA software systems carry a heavy burden. They help to ensure uptime, contain a wealth of recorded history, and represent a significant investment of development time. Despite this, backing up applications and their data remains a comparatively low priority. Standard backup strategies have limitations. Offline backups leave your system blind, while online backups can interfere with your process. Both leave gaps in your history when restoring backups, and both require specialized training. Advances in networking provide a more elegant solution. If your application includes one or more networked servers, you can build automatic real-time backups for history, configuration, alarms, and input/output (I/O) tags right into your server architecture. If those servers are in separate locations, you also have an off-site disaster backup of your whole application with no extra effort. If you are without a plan or fear the day you will need to put yours into motion, this article is for you. Traditional SCADA Backup Strategies Manual offline (cold) backups — This process is common for smaller SCADA systems. First, someone manually shuts down the system. Then, they save the whole application (or just the historical and configuration data) to a secure location like a tape device, hard drive, or network folder. When this is complete, they restart the application. Though relatively simple, this is a time-consuming process that usually takes place outside of regular business hours. For this reason, backups can be irregular or dropped entirely. Time-based offline (cold) backups — At regularly scheduled times, usually in the middle of the night, the SCADA application shuts down automatically and its data is exported to an SQL-based database format. This database is then recorded and archived as outlined above. Backing up offline ensures that files will not be corrupted if they are read while being updated by the running system. However, depending on the size and age of the application, this process can take anywhere from a couple of minutes to a couple of hours. All the while, operators cannot see their process displays. Alarms cannot be viewed, disseminated, or acknowledged. Thin client remote access is unavailable. Worst of all, process readings collected during this period will be permanently lost. Should the system fail and need to be restored, all process data and configuration changes logged since the last backup will also be lost. Time-based online (hot) backups — Online backups are useful for mission-critical systems where downtime is not an option. In this scenario, the monitoring and control process remains active while the application is being saved. This ensures that alarms are managed and operators are not left in the dark. However, this runs the risk of reading files while they are being written which can affect performance and corrupt the backup database. As with cold backups, restored databases will not include process or configuration data recorded since the last backup. Change-based online (hot) backups — Rather than updating the whole running application at once, the system backs up each change as it occurs. This eliminates the risk of losing data between backups but, like time-based hot backups, there is a risk of impeded performance and corruption as the backup process effectively "steps on the toes" of the running SCADA system. Other Issues With Traditional Backups Long-term compatibility of backup utilities — Though some SCADA software platforms include built-in tools for backing up historical and configuration data, others require third-party utilities. As these components are individually upgraded over time, they can cease to function together, which results in dropped backups or lost data. Specialized technical knowledge — Most backup methodologies require an SQL-based database format. SQL (structured query language) requires specialized knowledge to configure, backup, and restore. This means an investment of time and money for the system integrator or the internal IT department at each point of the process. A Better Way: Real-Time, Full-System Backup Simplified SCADA Redundancy Until recently, the cost of setting up and maintaining redundant servers with automatic failover was prohibitively expensive for most SCADA users. Modern monitoring and control software products not only make it easier to designate hot backups for fallen servers, 28 wateronline.com n Water Innovations A Better Way To Back Up SCADA How server architecture can automatically back up your whole supervisory control and data acquisition (SCADA) system