Managing the Historian (version 25)

Managing DataSets

A DataSet is a logical grouping of tags and is the basic building block of the Historian database. A DataSet houses the HDB (historic database) files that contain tags and all the TVQ (timestamp value quality) updates and properties for those tags. 

You may view all your DataSets by opening the Canary Admin client and selecting the Historian tile. The first screen of the Historian user interface displays every DataSet. 

HISTORIAN Window

In the upper left-hand corner you can view information about the Canary Historian.

DATASET Window

In the lower left-hand corner you can view information about the currently selected DataSet. To select a DataSet, click it once. It will be highlighted yellow once selected.

DataSet Options

When a DataSet is selected, the DATASET window has an additional set of options which can be displayed by selecting the down arrow icon. These options include:

If more DataSets exist than can be displayed, a scroll bar at the top of the screen appears. This bar can be used to navigate throughout the collection of DataSets and can be adjusted.  Either grip can be positioned along the range to start or end at a particular DataSet instance. Dragging the yellow bar between the grips will vary the DataSets displayed but not the number of DataSets displayed.

Managing HDB Files

When drilling into a specific DataSet, the next screen presents all the HDB files for that DataSet.

An HDB file contains all of the tags, TVQs, and metadata properties written to a DataSet for a specific period of time, usually one day. Within an HDB file, TVQs are grouped into blocks of records called vectors. Vector size and the number of TVQs segmented within a vector are dependent on data type.

When data begins to get logged to the DataSet, a new HDB file is automatically created and displayed. When an HDB file is finished having data written to it, it is rolled over, then validated and closed. A new HDB file is then automatically created. Anytime a logging session is stopped, an HDB file is closed and eventually validated by the background validation process. When the logging session is restarted, the current file is reopened for writing or a new HDB file is generated.

Additionally, HDB files will automatically roll over if they exceed 512 MB in size. It is best to avoid this scenario for optimal long-term performance which is why we recommend a max tag count of 25,000 tags per DataSet. This is a conservative limit and can be adjusted depending on the update rate and data types of the tags.

Each HDB file is represented by a tile with the date of the contained timestamps.  If there are more than one HDB files per day, the time the file was opened will also be displayed.

HDB File States and Indicators

HDB files have several states. Files that are online and available to be written to or queried from are dark blue. Files that are offline are gray.

If a tile displays a clock icon in the top-left corner, it either has not been validated yet as it is still being written to, or it has been modified since its last validation and needs validated again. Eventually the background validation process will validate the file.

If the tile displays a red question mark, the file is questionable and may be taken offline by the background validation. This can happen when the Historian service is abruptly terminated without being able to properly close the file it is writing to.

When an HDB tile is selected it will turn yellow if it is an online file or light grey if it is an offline file.  More than one HDB file may be selected using SHIFT or CTRL.

HDB File Validation

Validation is an internal Canary process that is generally executed automatically.  During HDB file validation, all file structure and data links are checked. If a file does not pass validation, it is automatically moved to an offline status.

HDB File Recovery

If an HDB file fails validation, the file must be recovered in order to be part of the available historical record. Once manually initiated, file recovery is an automated process that involves the following steps:

• The file is disassembled and all readable components are placed into text files
• An import file is created by reformatting the text files into the proper time sequence
• The new import file is then converted into an HDB file and brought online. At this point, the file should be manually validated to confirm it is no longer corrupt.
• The original corrupted HDB file is preserved and marked with a .old extension but remains outside the available historical record

HDB FILE Window

Based on the status indicator an admin should take the following action: 

HDB File Options

When an HDB tile is selected, the FILE window has an additional set of options which can be displayed by selecting the down arrow icon. These options are different based on the status of the HDB file.

Online HDB FILE OPTIONS 

Online HDB Files are represented by a blue tile. This is the default state of HDB files. Select a single HDB file or multiple HDB files using either Shift or the CTRL key.  Then select the down arrow icon in the FILE window to access the HDB file options.

Offline HDB FILE OPTIONS

Offline files are represented by gray tiles and have a different FILE OPTIONS menu. An HDB File is in an offline state when manually taken offline or if the validation process has found errors or corrupt values within an HDB file. Select a single HDB file or multiple HDB files using either Shift or the CTRL key then select the down arrow icon in the FILE window to access the HDB file options.

If more HDB files exist than can be displayed, a scroll bar at the top of the screen appears. This bar can be used to navigate throughout the collection of HDB files and can be adjusted.  Either grip can be positioned along the range to start or end at a particular HDB instance. Dragging the yellow bar between the grips will vary the HDB files displayed but not the number of HDB files displayed.

Managing Tags

TAGS Window

By double-clicking or selecting the yellow arrow on an HDB tile, the user can navigate to the Tags screen. The TAGS window is on the left side of the screen. 

1. Select a tag. Timestamps, Values, and Tag Qualities populate on the right side of the screen.

Select Trend to view the selected tag's TVQ updates on a quick trend chart.

Exporting a Tag List

The tag list can be exported as a CSV file by:

1. Select the down arrow icon beside the search bar in the TAGS window. 
2. Select Include Parent Path to prepend the tag with the DataSet name.
3. Select ok.

PROPERTIES Window

The PROPERTIES Window on the bottom left side of the screen, displays  additional tag information.  Tags that have metadata properties will have those properties displayed here.  (If metadata is configured to be stored in an external SQL database, they will not appear here, but they will appear in the Views tile.) Calculated tags, tags created using the Canary Calculation Server, will also display information. 

TAG OPTIONS

Select the drop down arrow in the PROPERTIES window.