User Guide

8
Trends
Trend Data Storage
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Siemens User Guide Version 2.1 A6V10415471_en_a_21
Building Technologies 2015-07-15
8.3 Trend Data Storage
Recorded trend data can be stored in three different locations:
 Offline Trendlog Objects : Offline trend data is saved in the automation station.
 Online Trendlog Objects : Contains the online trend data recorded and saved in
the management station.
 Archived Trend Database (not in version 2.0) : Contains all recorded Trend data
moved previously to the archive database.
Offline Trendlog Objects
Offline trend data can be recorded and saved by Trendlog objects within the
automation and control system even when the management station is not
connected. The recorded data can then be saved in the trend database. Offline
trend data can be retrieved and displayed in the trends.
Online Trendlog Objects
Data recorded by online trending and saved to the trend database (for example,
using save continuously) can be retrieved and displayed in the trends. Online
Trendlog objects record data also when the Trend View is closed.
Database Storage Capacity
In the database, 10 GB is saved for SQL Server Express and 250 GB of historical
data for SQL-Server. Once 90% of the database size is reached, the 10% oldest
data entries are deleted. The 10% of data for deletion always refers to the entire
time axis for the collected data. Thus, it cannot be exactly determined how many
entries or the database size that is actually deleted. Additional incoming entries are
rejected if the 10% of data entries cannot be deleted before reaching 98% of the
database size.
10
0
10 GB
90% of DB
# =10%
Time
GB
98% of DB
7
The data amount is comprised of the following:
 System activities
 Alarm messages
 Trend data
NOTE:
Additional information on data backup is available in the document System
Management Console
.