OADP-6249 note for kubevirt restore using ceph

Signed-off-by: Shruti Deshpande <shdeshpa@redhat.com>

Author: shdeshpa07

modules/oadp-restore-single-vm.adoc

@@ -39,4 +39,11 @@ spec:
 ----
 $ oc apply -f <restore_cr_file_name> # <1>
 ----
-<1> Specify the name of the `Restore` CR file.
+<1> Specify the name of the `Restore` CR file.
++
+[NOTE]
+====
+When you restore a backup of VMs, you might notice that the Ceph storage capacity allocated for the restore is higher than expected. This behavior is observed only during the `kubevirt` restore and if the volume type of the VM is `block`.
+
+Use the `rbd sparsify` tool to reclaim space on target volumes. For more details, see link:https://docs.redhat.com/en/documentation/red_hat_openshift_data_foundation/{product-version}/html/managing_and_allocating_storage_resources/reclaiming-space-on-target-volumes_rhodf[Reclaiming space on target volumes].
+====