As noted, this is not mandatory but we can do it and it's very fast.

This change also further untangles details about alertmanager and karma.

service/prometheus.md

@@ -2411,11 +2411,19 @@ transfer took somewhere between 2.5 and 3h.
 If even backups are destroyed, history will be lost, but the server should still
 recover and start tracking new metrics.
 
-Note that Alertmanager holds information about the current alert silences in
-place. If those are lost, we can recreate silences on a need-to basis. Karma
-does not hold specific state data, so nothing needs to be taken out of backups
-for it. Also, as long as prometheus is tracking metrics both services should
-both be working as well.
+As long as prometheus is tracking new metrics values Alertmanager and Karma
+should both be working as well.
+
+Alertmanager holds information about the current alert silences in place. This
+information is held in `/var/lib/alertmanager` and can be restored from backups.
+
+Restoring the Alertmanager directory from backups should only take a couple of
+seconds since it contains two very small files.
+
+If those are lost, we can recreate silences on a need-to basis.
+
+Karma polls Alertmanager directly so it does not hold specific state data. Thus,
+nothing needs to be taken out of backups for it.
 
 # Reference