diff --git a/lib/libzrepl/data_conn.c b/lib/libzrepl/data_conn.c
index e2881155e5b7..e65ffcdf49f1 100644
--- a/lib/libzrepl/data_conn.c
+++ b/lib/libzrepl/data_conn.c
@@ -41,6 +41,7 @@
 
 #define	MAXEVENTS 64
 
+#define	IO_THRESHOLD_TIME	30
 #define	ZVOL_REBUILD_STEP_SIZE  (10 * 1024ULL * 1024ULL * 1024ULL) // 10GB
 uint64_t zvol_rebuild_step_size = ZVOL_REBUILD_STEP_SIZE;
 
@@ -1787,6 +1788,7 @@ uzfs_zvol_io_ack_sender(void *arg)
 			}
 		}
 
+		latency = 0;
 		if (zio_cmd->hdr.opcode == ZVOL_OPCODE_READ) {
 			if (zio_cmd->hdr.status == ZVOL_OP_STATUS_OK) {
 				/* Send data read from disk */
@@ -1834,10 +1836,14 @@ uzfs_zvol_io_ack_sender(void *arg)
 				}
 			} else if (zio_cmd->hdr.opcode == ZVOL_OPCODE_SYNC) {
 				atomic_inc_64(&zinfo->sync_req_ack_cnt);
-				atomic_add_64(&zinfo->sync_latency,
-				    gethrtime() - zio_cmd->io_start_time);
+				latency = (gethrtime() -
+				    zio_cmd->io_start_time);
+				atomic_add_64(&zinfo->sync_latency, latency);
 			}
 		}
+		if ((latency >> 30) > IO_THRESHOLD_TIME)
+			LOG_INFO("IO %d with seq: %lu took %luns",
+			    zio_cmd->hdr.opcode, zio_cmd->hdr.io_seq, latency);
 		zinfo->zio_cmd_in_ack = NULL;
 		zio_cmd_free(&zio_cmd);
 	}