Agent's databases and storages

Frends Agents will always have SQLite installed with them. It is used to store, for example, configuration data. In addition to that, Frends Agents may use an external database from the SQL Server.

An Agent has different databases to store configuration data, cache log data and store a shared state between Agents inside of an Agent Group. When Agents inside of an Agent Group are configured to function as a High Availability (HA) Group (this is by default when there is more than one Agent), they require a shared state store to orchestrate File Watch, Schedule and Conditional Triggers.

Frends uses internal NuGet packages to deliver Processes and Tasks to Agents. The NuGet store is located in Azure Blob Storage. In the case of on-premises installations, the NuGet store is accessed through a file share.

Agent without bundled localdb

If you already have an SQL server installed, you do not need to download the bundled version of the Agent that includes localdb. When downloading this lighter version, you may install multiple Agents on the same machine. This can be useful when you, for example, want to run test and development Agents on the same machine.

Multiple Agents in an Agent Group

With a shared SQL database

If the Agent Group has a connection string set the Agents will use the shared SQL database and all Triggers are available in High Availability mode. This is the most common mode of installing multiple Agents in one Agent Group and should be used in most cases.

Without a shared SQL

If no connection string is set all the Agents will use a local database for storing configuration information. The first Agent will be "Primary Agent", this Agent will be able to execute all Triggers. The other Agents will be able to run HTTP, API and Service Bus Triggers. If this mode is selected, Schedule and File Triggers will not be run in High Availability mode. This mode of installation is useful if you do not have an SQL server but still want to have redundancy and load balancing for HTTP Processes.

File systems

The Agent requires access to the local file system for operation. It uses the local file system for storing Process deployment executables and SQLite databases. Storages listed on this page are available to cloud Agents. Some other drives may also be mounted to your system.

Each Agent Group has Azure file share that can be used to store files and share them within Agents in the same Agent Group.

It is mounted as the F drive or /frends-shared-data/.

Windows and stand-alone Linux Agents, but not Kubernetes Agents, have a local/managed 32 gb drive that is mounted as the G drive /frends-local-data/. It can be used to store files.

Frends Agents have a small internal drive that is used by operating systems and Frends, but it should not be used for storing other data. It is a C drive on Windows-based Agents.

The next article is Introduction to Frends Agent Group