You can access Filters under the Configure menu from the left-side menu bar. From here you can create a new filter or edit or delete an existing one.
Adding a New Filter
To add a filter, on the Filters page, click New Filter.
In the left upper corner specify a filter name. Be sure to specify a descriptive filter name so that you can identify the filter later in a drop-down list of other filters. Add additional explanations for what this filter is intended to accomplish.
While configuring a filter, you can set rules to ignore errors if specific conditions were met or ignore specific types of errors. You can also assign the filter to one or multiple devices at once from within the edit screen.
How to Filter Errors by Specific Conditions
In the Ignore an Error if the Following Conditions Apply section, you can specify multiple filters to help eliminate false positives and excessive alerts:
- Error is reported for less than (X) minutes – filters problems based on the frequency of an occurrence. For example, a five-minute setting filters out any problems that last for less than five minutes. Additionally, this option might be used for a brief rebooting of a web server when no alerts are desired.
- Error is not confirmed by at least (X) monitoring locations – filters errors based on the number of monitoring stations reporting the error. For example, a single monitoring station might not connect to a specific URL but other stations do connect, which signals that the problem lies with a backbone provider for that single station. Dotcom-Monitor recommends setting this filter value to two or higher to help filter out problems that are occurring on a specific backbone.
- Error is detected in less than (X) tasks – filter alerts based on the number of task errors occurring in a monitored device. For example, a monitoring device might consist of tasks that access three web servers in a server farm. If one of the servers fail, the device will still work as set up using only the remaining servers. By default, Dotcom-Monitor will send an alert because one server is unavailable. If the filter is set at two, an alert is sent only when two tasks in the device fail.
- Owner Device is Down – If you have selected an Owner Device for a particular device, errors for the device will be ignored if the owner device is currently returning errors or is unavailable. For example, 10 different websites may be monitored as 10 different monitoring devices, but all the websites may be dependent on a single router. If the router fails, all 10 websites will become unavailable, and, by default, Dotcom-Monitor will send an alert for each website as an individual monitoring device. If the filter option is activated, the error on the router will be ignored.
How to Filter Errors by Error Codes
You can set a filter to ignore specific error types in the Ignore an Errors with Specific Types and Codes section. Here you can filter out certain user-configurable errors. For example, DNS errors could be filtered out based on who is responsible for DNS server operations. You can create filters that will ignore specific errors that you know may occur and are not relevant to the goal of a specific device.
In addition, you can set up the system to ignore a range of error codes using a dash, or multiple error codes using semicolons as a separator.
Assigning a Filter to Devices
To assign a filter to one or several monitoring devices, go to the Assigned Devices section and select the device(s) from the list. The filter will be automatically applied to the selected devices. However, you can always set a corresponding filter while configuring device alert settings.