diff --git a/onlyoffice/metadata.yml b/onlyoffice/metadata.yml
index 6914d74..1d815cc 100644
--- a/onlyoffice/metadata.yml
+++ b/onlyoffice/metadata.yml
@@ -38,3 +38,24 @@ uses:
     auto: summon
     solves:
       database: "main storage"
+
+  ## XXXvlab: this should not be necessary as official documentation
+  ## seems to explain that all data are either logs or caches. But we
+  ## had issues with onlyoffice not sending back modifications to the
+  ## filesystem. With some tweaks, we can sometimes gets the data from
+  ## application cache.  So for now, we must include this data to
+  ## backup.
+  backup:
+    constraint: recommended
+    auto: pair
+    solves:
+      backup: "Automatic regular backups of dumps"
+    default-options:
+      ## First pattern matching wins, no pattern matching includes.
+      ## include-patterns are checked first, then exclude-patterns
+      ## Patterns rules:
+      ##  - ending / for directory
+      ##  - '*' authorized
+      ##  - must start with a '/', will start from $SERVICE_DATASTORE
+      include-patterns:
+        - /var/lib/onlyoffice/