# Diagnostics Diagnostic variables are available for store operation diagnostics. They are represented as OPC UA items and described below. Only diagnostic variables that are common for all types of stores are described here: ![](/files/SCmbilg0ZH1ldnQfywwg) * **GoodResponses:** contains the total number of successful responses from the database when preparing or writing data. * **LastResponseUtcTime:** contains the time of the last successful response from the database in the UTC format. * **BadResponses:** contains the total number of unsuccessful or unreceived (during loss of connection) responses from the database. * **LastErrorUtcTime:** contains the time of the last unsuccessful or unreceived response from the database in the UTC format. * **HasError:** indicates whether the last request sent to the database was successful or not. * **DemoIsExpired:** contains that demonstration period for the store is expired. * **MaxWriteDuration:** contains the longest time interval between sending a write request and receiving a response. * **MaxPrepareDuration:** contains the longest time interval between sending a database preparation request and receiving a response. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.monokot.io/time-series-and-stores/stores/diagnostics.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.