diff --git a/src/lib_storage/raw_store.ml b/src/lib_storage/raw_store.ml
index 5f17fa4c4..6df7410e2 100644
--- a/src/lib_storage/raw_store.ml
+++ b/src/lib_storage/raw_store.ml
@@ -66,7 +66,19 @@ let (>>=?) v f =
 
 let init ?mapsize path =
   if not (Sys.file_exists path) then Unix.mkdir path 0o755 ;
-  match Lmdb.opendir ?mapsize ~flags:[NoTLS; NoMetaSync] path 0o644 with
+  let sync_flag =
+    match Sys.getenv_opt "TEZOS_STORE_SYNC" with
+    | None -> []
+    | Some s ->
+        match String.lowercase_ascii s with
+        | "nosync" -> [ Lmdb.NoSync ]
+        | "nometasync" -> [ Lmdb.NoMetaSync ]
+        | _ ->
+            Printf.eprintf "Unrecognized TEZOS_SYNC option : %s\n\
+                            allowed: nosync nometasync" s;
+            []
+  in
+  match Lmdb.opendir ?mapsize ~flags:(sync_flag @ [NoTLS; NoMetaSync]) path 0o644 with
   | Ok dir -> return { dir ; parent = Lwt.new_key () }
   | Error err -> failwith "%a" Lmdb.pp_error err
 
diff --git a/vendors/irmin-lmdb/irmin_lmdb.ml b/vendors/irmin-lmdb/irmin_lmdb.ml
index 21abebb5b..9bf0f1452 100644
--- a/vendors/irmin-lmdb/irmin_lmdb.ml
+++ b/vendors/irmin-lmdb/irmin_lmdb.ml
@@ -677,7 +677,19 @@ module Make
         let root = match root with None -> "irmin.ldb" | Some root -> root in
         if not (Sys.file_exists root) then Unix.mkdir root 0o755 ;
         let flags = if readonly then [ Lmdb.RdOnly ] else [] in
-        let flags = Lmdb.NoRdAhead :: Lmdb.NoTLS :: flags in
+        let sync_flag =
+          match Sys.getenv_opt "TEZOS_CONTEXT_SYNC" with
+          | None -> []
+          | Some s ->
+              match String.lowercase_ascii s with
+              | "nosync" -> [ Lmdb.NoSync ]
+              | "nometasync" -> [ Lmdb.NoMetaSync ]
+              | _ ->
+                  Printf.eprintf "Unrecognized TEZOS_SYNC option : %s\n\
+                                  allowed: nosync nometasync" s;
+                  []
+        in
+        let flags = sync_flag @ Lmdb.NoRdAhead :: Lmdb.NoTLS :: flags in
         let file_flags = if readonly then 0o444 else 0o644 in
         match Lmdb.opendir ~mapsize ~flags root file_flags with
         | Error err -> Lwt.fail_with (Lmdb.string_of_error err)