Opinion: Do you need a $60,000 process historian to log data? (Control Engineering)

Interesting article featured on Control Engineering

-- Control Engineering, 3/26/2009
Steve Hechtman, Inductive Automation

I wish to register a complaint. There is a rumor that has been circulating for years that relational databases are too slow for fast process data and that only process historians are up to the job. Vendors of process historians will cite sluggish performance and the lack of data compression as the reasons standard off-the-shelf relational databases won’t work. Apparently the last time they used a SQL relational database was a few decades ago.

While there may be some specialized domains where process historians have a niche, they are not a practical choice for most industrial applications. In effect, historian vendors are saying your Toyota Camry is inappropriate transportation because it is incapable of going 180 mph or finishing the quarter mile in under 10 seconds.

The rumor denigrating relational databases for poor throughput is baseless. A standard, off-the-shelf Microsoft SQL Server coupled with FactorySQL can log in excess of 100,000 tags per second using a desktop machine. In all likelihood, other factors such as the industrial network would become bottlenecks before the database does. Furthermore, today’s generation of SQL relational databases are designed to scale gracefully to power high-volume Website traffic, whose load peaks dwarf those of industrial controls applications.

Data compression is an area where process historians do score a point. However, even this consideration can be handled with standard off-the-shelf SQL relational databases. Take a look at the MySQL 5.0 Archive Storage Engine which achieves on average a four to one compression ratio. Proprietary process historians may beat that, but let’s get back to the point of practicality. Hard disk space is so cheap these days that even considering this point is becoming an anachronism. For the rare application that demands it, table compression coupled with intelligent data logging allow databases to compete even in this regard.

One crucial question that process historian vendors omit is: what are IT departments willing to support? When I make initial contact with IT folks, I always ask which relational database they use. Then I assure them we’ll work with that. This generally makes them very happy. Believe me, you want IT on your side or your project will end up on a data island which is useless in an enterprise system. Think of it from their point view; they have the training and tools, generally, to support just one type of database. With these tools and training they can support the database with scheduled backups, tuning and other maintenance.

Okay, we’ve heard process historian rants about relational databases; let’s talk about the downside of process historians. Let’s start with support. Just check the Amazon bookstore for any one of the proprietary process historians and you’re likely to come up empty handed. On the other hand, check for “SQL configuration” and you’ll come up with hundreds of books. How about finding people to support these proprietary systems? Good luck.

Then there is the concern about supporting relational data with a process historian. Frankly, the middleware layer is all about relational data. Time-series data, which is what process historians deal with, is just a fraction of what is needed in the middleware layer. Correlating batches, shifts, inventory, orders, downtime, quality, etc., is purely relational in nature, and these are the features that today’s enterprise integration projects demand.

What about a cost comparison? The process historian is going to be ten to thirty times the cost of a relational database using a driver like FactorySQL depending on the number of tags required. The controls industry is still backwards on this point and prefers to price its software per tag as though the extra tags cost money to manufacture.

In summary, we’re talking about practical choices. The Ferrari may be great fun, but do you need a $500,000 vehicle to drive the kids to school or would the Camry suffice? Likewise, do you need a $60,000 process historian to log data? A relational database makes a great historian, but the reverse isn’t true. A process historian cannot process relational data. For the vast majority of systems, a relational database has more than enough power to service the historical and relational data requirements, making it not just the practical, but the wise choice.

SCADA cyber security

Wurldtech is all about SCADA security - I'm pretty sure their labs released the Wonderware and Citect exploits. They have a vulnerability database called Achilles Delphi. Not to mention their very cool looking Satellite test device. 

http://www.wurldtech.com/

Wonderware selects Kepware as endorsed partner for expanding device communications offerings

Wonderware selects Kepware as endorsed partner for expanding device communications offerings. They're offering a branded version of KepServer Ex as "Kepware for Wonderware".

This move leads me to wonder if Kepware plans on supporting Archestra or if Wonderware made the intelligent decision of "3rd partnering" OPC connectivity. The latter makes sense since Kepware supports such a wide variety of devices, and, frankly, is so much better at device drivers than Wonderware.

Rockwell did it, why not Wonderware. I'm a fan of collaboration and standardization. Sounds good to me.

http://www.pandct.com/media/shownews.asp?ID=18531

Opto 22 leveraging web 2.0

Walt reports on Opto22 utilizing web videos "optovideos" and other web technology user education.

http://www.controlglobal.com/soundoff/?p=3481

OPC UA Coming to life!

Lots more OPC UA buzz - looks like it'll be really materializing soon - hopefully later this year. I personally can't wait! Remember, Iconics and Kepware already pledged to bring an end to end UA solution soon.

http://www.controleng.com/article/CA6559411.html?rssid=129

Edit - more contributions pointed out by Eric Murphy of Matrikon
http://www.ceasiamag.com/article-3936-theyearofopcua-LogisticsAsia.html
Automation.com OPC portal

FireFox Download Day announced

Tuesday, 17JUN is Download Day (FireFox 3 if you havn't been paying attention)! Check out a graphical world pledge map here.

Industry news update

Quick summary of industry news, compliments of InTech Editor Greg Hale's Blog. Thanks for the great info!


Wonderware - Predicting growth in Africa. Still working on India, China and Eastern Europe, but Africa's where it's at in the next 30 years or sooner. Full entry here.

Kepware - Partnering with Oracle and adding an OPC Client to their flagship OPC Server KepServer Ex to all pass through support for 3rd party OPC servers including diagnostics. Exciting! Full entry here.

Rockwell/Cisco partnership - release Rockwell branded Cisco Catalyst switches that offer easier configuration, configuration via RSLogix 5000, and pre-canned support for common (Rockwell Centric) Industrial Networking protocols as CIP and Ethernet/IP (Industrial Protocol). It's about DAMNED TIME! I've always said that AB makes good PLCs. They're finally leveraging developed technology for industrial applications instead of reinventing the wheel over and over! That said, I'd fear the price tag! Full entry here.