Guidelines for Setting Archive Size

Since archived data files can become quite large, you must adjust system parameters carefully to limit data collection to meaningful data only and thus minimize the required size of system storage. You can allocate up to 256 GB per archive.

For each archive, you need approximately 1MB of archive space for every 1000 tags to store tag information. Archive size is a function of the rate at which you archive data and the time period you want the archive to cover. A typical user wants the archive to cover a time period of, say, 30 days.

The following factors affect the rate at which you archive data:

Number of tags
Polling frequency of each tag
Compression settings
Data types

Based on these parameters, the archive size is calculated as follows:

Calculating Archive Size

Suppose you want to store data, and you have the following parameters:

Number of tags: 5000
Polling rate: 1 value/5 seconds
Pass compression: 5%.
Pass compression is the number of data values archived relative to the number of values read.
Bytes/value: 4
Duration: 30 days

Based on the preceding formula, for the given parameters, the archive size is calculated as follows:

The calculation shows that a file size of 500 MB is adequate for archiving one month of data for this application.

Therefore, we recommend that you set the default archive size to 500 MB for systems with 1000 tags or more. If you believe the computed size is too large for your application, you can modify parameters as follows:

Decrease the polling frequency.
Increase compression deadband, reducing the pass percentage.
Reduce the number of tags.
Add more disk capacity to your computer.

Archive Size Calculator

An archive size calculator tool is available to estimate archive size and collector compression based on a tag that has already been configured or based on your inputs. Log on to http://digitalsupport.ge.com to download this tool and other GE Intelligent Platforms freeware product solutions.