Zabbix Documentation 2.2

2.23.04.04.2 (current)In development:4.4 (devel)Unsupported:1.82.02.43.23.4

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manual:config:items:history_and_trends

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manual:config:items:history_and_trends [2013/07/15 07:00]
martins-v history/trends can be set through housekeeper settings
manual:config:items:history_and_trends [2016/03/15 05:56] (current)
martins-v raising note level to important
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 You can set for how many days history will be kept:  You can set for how many days history will be kept: 
  
-  * in the item properties form+  * in the item properties ​[[:​manual/​config/​items/​item|form]]
   * when mass-updating items   * when mass-updating items
-  * when [[:2.2/manual/web_interface/frontend_sections/administration/general#​housekeeper|setting up]] Housekeeper ​tasks+  * when [[manual:web_interface:frontend_sections:administration:general#​housekeeper|setting up]] housekeeper ​tasks
  
-Any older data will be removed by the Housekeeper.+Any older data will be removed by the housekeeper.
  
 The general strong advice is to keep history for the smallest possible number of days and that way not to overload the database with lots of historical values. The general strong advice is to keep history for the smallest possible number of days and that way not to overload the database with lots of historical values.
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 Instead of keeping a long history, you can keep longer data of trends. For example, you could keep history for 14 days and trends for 5 years. ​ Instead of keeping a long history, you can keep longer data of trends. For example, you could keep history for 14 days and trends for 5 years. ​
  
-You can get a good idea of how much space is required by history versus trends data by referring to the [[:2.2/manual/installation/requirements#​database_size|database sizing page]].+You can get a good idea of how much space is required by history versus trends data by referring to the [[manual:installation:requirements#​database_size|database sizing page]].
  
 While keeping shorter history, you will still be able to review older data in graphs, as graphs will use trend values for displaying older data. While keeping shorter history, you will still be able to review older data in graphs, as graphs will use trend values for displaying older data.
  
-<​note>​If history is set to '​0', ​Zabbix ​will only be able to calculate triggers that check the last valueHistorical values would not be stored in the database at all, except for the last value for the item itself.</​note>​+<​note ​important>If history is set to '​0', ​the item will update ​only inventoryNo trigger functions will be evaluated.</​note>​
  
 === Keeping trends === === Keeping trends ===
  
-Trends is a built-in historical data reduction mechanism ​where for every hour minimum, maximum and average values are stored, as well as the total number of values ​in that hour. +Trends is a built-in historical data reduction mechanism ​which stores ​minimum, maximum, average ​and the total number of values ​per every hour for numeric data types
  
 You can set for how many days trends will be kept:  You can set for how many days trends will be kept: 
-  * in the item properties form+  * in the item properties ​[[:​manual/​config/​items/​item|form]]
   * when mass-updating items   * when mass-updating items
   * when setting up Housekeeper tasks   * when setting up Housekeeper tasks
  
-Trends usually can be kept for much longer than history. Any older data will be removed by the Housekeeper.+Trends usually can be kept for much longer than history. Any older data will be removed by the housekeeper.
  
-<​note>​If trends are set to '​0',​ Zabbix server does not calculate or store trends at all.</​note>​+<​note ​important>If trends are set to '​0',​ Zabbix server does not calculate or store trends at all.</​note>​
  
 +<​note>​The trends are calculated and stored with the same data type as the original values. As the result the average value calculations of unsigned data type values are rounded and the less the value interval is the less precise the result will be. For example if item has values 0 and 1, the average value will be 0, not 0.5.
 +
 +Also restarting server might result in the precision loss of unsigned data type average value calculations for the current hour.</​note>​