diff --git a/kernel/mars_cksum.c b/kernel/mars_cksum.c
index 8c411e24..bc1d156a 100644
--- a/kernel/mars_cksum.c
+++ b/kernel/mars_cksum.c
@@ -163,10 +163,14 @@ void cksum_do_finish(struct cksum_mref_aspect *mref_a, int error)
 			struct mref_object *mref = mref_a->object;
 
 			atomic_inc(&brick->total_errors);
-#if 1
-			MARS_ERR("CKSUM MISMATCH status=%d pos=%lld len=%d\n",
-				 status, mref->ref_pos, mref->ref_len);
-#endif
+			if (brick->report_errors) {
+				MARS_ERR("CKSUM MISMATCH status=%d pos=%lld len=%d\n",
+					 status, mref->ref_pos, mref->ref_len);
+			}
+			/* Hard blocking exactly where it is */
+			while (brick->block_on_errors) {
+				brick_msleep(100);
+			}
 		}
 	}
 }
diff --git a/kernel/mars_cksum.h b/kernel/mars_cksum.h
index 5870888b..0a694378 100644
--- a/kernel/mars_cksum.h
+++ b/kernel/mars_cksum.h
@@ -46,6 +46,10 @@ struct cksum_mref_aspect {
 
 struct cksum_brick {
 	MARS_BRICK(cksum);
+	/* parameters */
+	bool report_errors;
+	bool block_on_errors;
+	/* statistics */
 	atomic_t total_reads;
 	atomic_t total_writes;
 	atomic_t total_small_reads;
diff --git a/kernel/sy_old/mars_main.c b/kernel/sy_old/mars_main.c
index 25625d40..d88faf2a 100644
--- a/kernel/sy_old/mars_main.c
+++ b/kernel/sy_old/mars_main.c
@@ -341,6 +341,8 @@ const char *rot_keys[] = {
 	"inf-fetch",
 	// from make_sync()
 	"inf-sync",
+	// from make_bio()
+	"err-cksum",
 	// from make_log_step()
 	"wrn-log-consecutive",
 	// from make_log_finalize()
@@ -4036,8 +4038,21 @@ int make_bio(void *buf, struct mars_dent *dent)
 				       cksum_name);
 
 		MARS_INF("cksum %p\n", brick);
-		if (brick)
+		if (brick) {
+			struct cksum_brick *cksum_brick = (void*)brick;
+			int err_count;
+
 			brick->killme = true;
+			cksum_brick->report_errors = true;
+			cksum_brick->block_on_errors =
+				_check_allow(global, dent->d_parent, "pause-cksum");
+			err_count = atomic_read(&cksum_brick->total_errors);
+			if (err_count > 0) {
+				make_rot_msg(rot, "err-cksum",
+					     "There are %d CKSUM errors",
+					     err_count);
+			}
+		}
 		brick_string_free(bio_name);
 	}