diff --git a/pkg/operator/ceph/file/mds/config.go b/pkg/operator/ceph/file/mds/config.go
index 618976c6d..13cf0a1b7 100644
--- a/pkg/operator/ceph/file/mds/config.go
+++ b/pkg/operator/ceph/file/mds/config.go
@@ -74,6 +74,9 @@ func (c *Cluster) setDefaultFlagsMonConfigStore(mdsID string) error {
 	if !c.fs.Spec.MetadataServer.Resources.Limits.Memory().IsZero() {
 		mdsCacheMemoryLimit := float64(c.fs.Spec.MetadataServer.Resources.Limits.Memory().Value()) * mdsCacheMemoryLimitFactor
 		configOptions["mds_cache_memory_limit"] = strconv.Itoa(int(mdsCacheMemoryLimit))
+	} else if !c.fs.Spec.MetadataServer.Resources.Requests.Memory().IsZero() {
+		mdsCacheMemoryRequest := float64(c.fs.Spec.MetadataServer.Resources.Requests.Memory().Value()) * mdsCacheMemoryResourceFactor
+		configOptions["mds_cache_memory_limit"] = strconv.Itoa(int(mdsCacheMemoryRequest))
 	}
 
 	// Set mds_join_fs flag to force mds daemon to join a specific fs
diff --git a/pkg/operator/ceph/file/mds/spec.go b/pkg/operator/ceph/file/mds/spec.go
index 4c3243756..56d146660 100644
--- a/pkg/operator/ceph/file/mds/spec.go
+++ b/pkg/operator/ceph/file/mds/spec.go
@@ -37,7 +37,8 @@ const (
 	// MDS cache memory limit should be set to 50-60% of RAM reserved for the MDS container
 	// MDS uses approximately 125% of the value of mds_cache_memory_limit in RAM.
 	// Eventually we will tune this automatically: http://tracker.ceph.com/issues/36663
-	mdsCacheMemoryLimitFactor = 0.5
+	mdsCacheMemoryLimitFactor    = 0.5
+	mdsCacheMemoryResourceFactor = 0.8
 )
 
 func (c *Cluster) makeDeployment(mdsConfig *mdsConfig, namespace string) (*apps.Deployment, error) {