diff --git a/pbs-api-types/src/maintenance.rs b/pbs-api-types/src/maintenance.rs
index dd3de50a..2102cf2c 100644
--- a/pbs-api-types/src/maintenance.rs
+++ b/pbs-api-types/src/maintenance.rs
@@ -20,8 +20,17 @@ pub const MAINTENANCE_MESSAGE_SCHEMA: Schema =
 #[derive(Clone, Copy, Debug)]
 /// Operation requirements, used when checking for maintenance mode.
 pub enum Operation {
+    /// for any read operation like backup restore or RRD metric collection
     Read,
+    /// for any write/delete operation, like backup create or GC
     Write,
+    /// for any purely logical operation on the in-memory state of the datastore, e.g., to check if
+    /// some mutex could be locked (e.g., GC already running?)
+    ///
+    /// NOTE: one must *not* do any IO operations when only helding this Op state
+    Lookup,
+
+    // GarbageCollect or Delete?
 }
 
 #[api]
@@ -29,6 +38,12 @@ pub enum Operation {
 #[serde(rename_all = "kebab-case")]
 /// Maintenance type.
 pub enum MaintenanceType {
+    // TODO:
+    //  - Add "unmounting" once we got pluggable datastores
+    //  - Add "GarbageCollection" or "DeleteOnly" as type and track GC (or all deletes) as separate
+    //    operation, so that one can enable a mode where nothing new can be added but stuff can be
+    //    cleaned
+
     /// Only read operations are allowed on the datastore.
     ReadOnly,
     /// Neither read nor write operations are allowed on the datastore.
@@ -65,7 +80,9 @@ impl MaintenanceMode {
             .decode_utf8()
             .unwrap_or(Cow::Borrowed(""));
 
-        if self.ty == MaintenanceType::Offline {
+        if let Some(Operation::Lookup) = operation {
+            return Ok(());
+        } else if self.ty == MaintenanceType::Offline {
             bail!("offline maintenance mode: {}", message);
         } else if self.ty == MaintenanceType::ReadOnly {
             if let Some(Operation::Write) = operation {