DOCSP-46244 backup daemon definition (#660)

Author: kyuan-mongodb

source/core/system-overview.txt

@@ -44,12 +44,12 @@ For a list of |onprem|'s default ports and health-check endpoints, see
 Backup Daemon Service
 ---------------------
 
-You can configure any |onprem| instance to run the :term:`Backup
-Daemon` service to back up MongoDB databases.
-
-To learn how to start, check the status of, stop, and restart the Backup
-daemon on a server, see :ref:`Start and Stop the Backup Daemon
-<start-stop-backup-daemon>`.
+You can configure any |onprem| instance to perform backup :term:`snapshot`
+maintenance work, such as a :term:`grooms <groom>` and managing
+file system snapshot files on the :term:`file system store <File System
+Store>` by running the :term:`Backup Daemon`. To learn how to start,
+check the status of, stop, and restart the Backup Daemon on a server,
+see :ref:`Start and Stop the Backup Daemon <start-stop-backup-daemon>`.
 
 How the Backup Daemon performs depends upon the
 :manual:`MongoDB version compatibility</reference/command/setFeatureCompatibilityVersion>`
@@ -65,11 +65,11 @@ The Backup Daemon service provides the following services for databases:
 - Performs some state updates to the backup job
 - Perform a queryable restore
 
-The daemon does scheduled work based on data coming into the |onprem|
-from the {+mdbagent+}s. Client applications can't communicate with the
-daemon. Its state and job queues come from the
-:ref:`mms-application-database`. |mms| creates snapshots from the
-database being backed up. 
+Client applications can't communicate with the daemon. Its state and job
+queues come from the :ref:`mms-application-database`. |mms| creates
+snapshots from the database being backed up. For incremental backups
+using file system stores, the daemon is responsible for creating
+snapshots.
 
 :ref:`Multiple Backup Daemons <multiple-backup-daemons>` can scale
 horizontally to run more concurrent jobs when needed and can provide

source/reference/glossary.txt

@@ -113,9 +113,14 @@ Glossary
 
 
    Backup Daemon
-      The |onprem| uses :manual:`backup cursors
-      </reference/glossary/#std-term-backup-cursor>` instead of
-      :opsmgr:`head databases </reference/glossary/#std-term-head-database>`. 
+      A required headless service to the |mms| Application that is
+      responsible for backup :term:`snapshot` maintenance work, such as
+      a :term:`groom` and managing file system snapshot files on the
+      :term:`file system store <File System Store>`
+
+      While we no longer use a :term:`head database` for backup
+      snapshots, Backup Daemons are still a required component for
+      |mms| backups and :term:`queryable backup` to function.
 
       .. seealso::