> NOTE: If you're not seeing the `Data Sources` link in your side menu it means that your current user does not have the `Admin` role for the current organization.
Access mode controls how requests to the data source will be handled. Server should be the preferred way if nothing else stated.
### Server access mode (Default)
All requests will be made from the browser to Grafana backend/server which in turn will forward the requests to the data source and by that circumvent possible Cross-Origin Resource Sharing (CORS) requirements. The URL needs to be accessible from the grafana backend/server if you select this access mode.
### Browser access mode
All requests will be made from the browser directly to the data source and may be subject to Cross-Origin Resource Sharing (CORS) requirements. The URL needs to be accessible from the browser if you select this access mode.
Some functions like aliasByNode support an optional second argument. To add this parameter specify for example 3,-2 as the first parameter and the function editor will adapt and move the -2 to a second parameter. To remove the second optional parameter just click on it and leave it blank and the editor will remove it.
You can reference queries by the row “letter” that they’re on (similar to Microsoft Excel). If you add a second query to a graph, you can reference the first query simply by typing in #A. This provides an easy and convenient way to build compounded queries.
Graphite 1.1 introduced tags and Grafana added support for Graphite queries with tags in version 5.0. To create a variable using tag values, then you need to use the Grafana functions `tags` and `tag_values`.
Query | Description
------------ | -------------
*tags()* | Returns all tags.
*tags(server=~backend\*)* | Returns only tags that occur in series matching the filter expression.
*tag_values(server)* | Return tag values for the specified tag.
Multi-value variables in tag queries use the advanced formatting syntax introduced in Grafana 5.0 for variables: `{var:regex}`. Non-tag queries will use the default glob formatting for multi-value variables.
Example of a tag expression with regex formatting and using the Equal Tilde operator, `=~`:
```text
server=~${servers:regex}
```
Checkout the [Advanced Formatting Options section in the Variables]({{< relref "reference/templating.md#advanced-formatting-options" >}}) documentation for examples and details.
queries via the Dashboard menu / Annotations view.
Graphite supports two ways to query annotations. A regular metric query, for this you use the `Graphite query` textbox. A Graphite events query, use the `Graphite event tags` textbox,
It's now possible to configure datasources using config files with Grafana's provisioning system. You can read more about how it works and all the settings you can set for datasources on the [provisioning docs page](/administration/provisioning/#datasources)