Explain the importance of checkpointing for backups

modules/ROOT/pages/backup-restore/online-backup.adoc

@@ -263,6 +263,19 @@ For example, if your current database has a `Total mapped size` of `128GB` as pe
 [[online-backup-resources]]
 === Computational resource configurations
 
+Checkpointing::
+
+Remember that a backup job triggers a checkpoint if needed.
+The backup cannot proceed until the checkpoint finishes.
++
+While the server is checkpointing, the backup job does not receive any data.
+To adjust the backup timeout, configure the xref:configuration/configuration-settings.adoc#config_dbms.cluster.catchup.client_inactivity_timeout[`dbms.cluster.catchup.client_inactivity_timeout`] setting, which restricts how long the network can be inactive.
+You can also tune up xref:configuration/configuration-settings.adoc#_checkpoint_settings[the Checkpoint settings] if backups are timing out due to checkpointing.
++
+Periods of high traffic may impact the duration of checkpointing -- and thus the success of a backup job.
++
+For more details on the checkpointing policy, see xref:database-internals/checkpointing.adoc[Database internals -> Checkpointing and log pruning].
+
 Transaction log files::
 The xref:database-internals/transaction-logs.adoc[transaction log files], which keep track of recent changes, are rotated and pruned based on a provided configuration.
 For example, setting `db.tx_log.rotation.retention_policy=3` files keeps 3 transaction log files in the backup.