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The Benefit of Local Logging

Nov 30, 2017

The ninth edition of a weekly Question and Answer column with Gary Stern, President and Founder of Canary Labs. Have a question you would like me to answer? Email askgary@canarylabs.com  


Dear C.S.,

While you certainly could keep the Logger in the cloud we usually recommend logging data at the local source rather than logging data remotely.  By local source, we mean installing the Canary Logger and Sender Service on the same machine as the OPC server.  Even though the overall purpose of most cloud applications can vary, there are two major benefits to logging locally.
First, is the advantage of the Canary Store and Forward Service which is comprised of two components, the Sender and the Receiver.  The Sender Service is designed to move information to the Receiver which is installed local to the Canary Data Historian.  If contact is lost between the Sender and Receiver Service, the Sender Service will cache data to local disk. When communications return, the cached data is transferred to the historian in time-sequence order and removed from the Sender Service.  This prevents data loss due to network issues and also allows you to take the historian offline for version updates or maintenance as needed.
Secondly, when installed locally, the Logger communicates to the OPC server via COM.  When installed remotely, it will use DCOM to communicate.  DCOM requires a dynamic port range, making it firewall unfriendly.  You should always pick you IT battles wisely, this is one you would probably not win.
Your question does bring up an interesting side point.  The IIoT push is driving more and more "non-traditional" Canary installs.  We are working with many clients that are leveraging cloud solutions to grab just a small handful of data points from a multitude of sites.  Overall, you must look at your individual application and decide how important is the data, are there potential security risks, and are additional hardware costs justified.  If the largest concern are hardware costs, you might be interested to know that we have successfully logged data from small Linux devices like the Raspberry Pi.

We are here to offer further support as needed, we would love to talk through your individual needs.  

Sincerely,
Gary Stern
President and Founder
Canary Labs


Have a question you would like me to answer?  Email askgary@canarylabs.com

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