The Data Store Details Section
The Statistics Subsection
| Field | Description |
|---|---|
| Archive Compression (% compression) | Displays the current effect of archive data compression. If the
value is zero, it indicates that archive compression is either
ineffective or turned off. To increase the effect of data
compression, increase the value of archive compression deadbands on
individual tags in the Tag Maintenance section to activate
compression. In calculating the effect of archive compression, Historian counts internal system tags as well as data source tags. Therefore, when working with a very small number of tags and with compression disabled on data source tags, this field may indicate a value other than zero. If you use a realistic number of tags, however, system tags will constitute a very small percentage of total tags and will therefore not cause a significant error in calculating the effect of archive compression on the total system. |
| Write Cache Hit | Displays the hit ratio of the write cache in percentage of total writes. It is a measure of how efficiently the system is collecting data. Typically, this value should range from 95 to 99.99%. If the data is changing rapidly over a wide range, however, the hit percentage drops significantly because current values differ from recently cached values. More regular sampling may increase the hit percentage. Out-of-order data also reduces the hit ratio. |
| Receive Rate | Displays how busy the server is at a given instance and the rate at which the server is receiving data from collectors. |
| Free Space (MB) | Displays how much disk space (in MB) is left in the current archive. |
| Consumption Rate (MB/day) | Displays how fast the archive disk space is consumed. If the value is too high, you can reduce it by slowing the poll rate on selected tags or data points or by increasing the filtering on the data (widening the compression deadband to increase compression). |
| Messages Since Startup | Not applicable |
| Failed Writes | Displays the number of samples that failed to be written. Since
failed writes are a measure of system malfunctions or an indication
of offline archive problems, this value should be zero. If you
observe a non-zero value, investigate the cause of the problem and
take corrective action. Historian also generates a message if a write fails. Note that the message only appears once per tag, for a succession of failed writes associated with that tag. For example, if the number displayed in this field is 20, but they all pertain to one Historian tag, you will only receive one message until that Historian tag is functional again. |
| Est Days to Full (Days) | Displays how much time is left before the archive is full, based
on the current consumption rate. This value is dynamically
calculated by the server and becomes more accurate as an archive
file gets closer to completion. This value is only an estimate and
will vary based on a number of factors, including the current
compression effectiveness. The System sends messages notifying you
at 5, 3, and 1 days until full. After the archive is full, a new
archive must be created (could be automatic). To increase this value, you must reduce the consumption rate. To ensure that collection is not interrupted, make sure that the Automatically Create Archives option is enabled in the Data Store Maintenance section (under Global Options). You may also want to enable the Overwrite Old Archives option if you have limited disk capacity. Enabling overwrite, however, means that some old data will be lost when new data overwrites the data in the oldest online archive. Use this feature only when necessary. |
| Alerts Since Startup | Not applicable |
The User Settings Subsection
| Field | Description |
|---|---|
| Data Store State | The current state of the data store. The value in this field is Running until you delete the data store. |
| Is System | Indicates whether this data store is the system data store.
Note: By default, the Is System value of
the system data store is set to yes. You
cannot set the Is System value of any
historical data store to yes.
|
| Number of Tags | Displays the number of tags the data store contains. |
| Is Default (Yes/No) | Indicates whether the data store is the default store. Select Yes to set this data store as default one. |
| Storage Type | Indicates whether the storage type is historical or SCADA buffer. |
| Description | The description of the data store. |