diff --git a/brick.c b/brick.c
index 28aa47b1..54aa5de4 100644
--- a/brick.c
+++ b/brick.c
@@ -789,16 +789,30 @@ int set_recursive_button(struct generic_brick *orig_brick, brick_switch_t mode,
 		BRICK_DBG("--> switch '%s' stack = %d\n", SAFE_STR(brick->brick_name), stack);
 		set_button_wait(brick, val, force, timeout);
 		if (val ? !brick->power.led_on : !brick->power.led_off) {
-			BRICK_DBG("switching to %d: brick '%s' not ready (%s)\n", val, SAFE_STR(brick->brick_name), SAFE_STR(orig_brick->brick_name));
+			BRICK_ERR("switching '%s' to %d: brick not ready (%s)\n", SAFE_STR(brick->brick_name), val, SAFE_STR(orig_brick->brick_name));
 			goto done;
 		}
 
-		if (force && !val && (mode == BR_FREE_ONE || mode == BR_FREE_ALL) && brick->free) {
+		if (force && !val && (mode == BR_FREE_ONE || mode == BR_FREE_ALL)) {
+			int i;
 			BRICK_DBG("---> freeing '%s'\n", SAFE_STR(brick->brick_name));
-			status = brick->free(brick);
-			if (status < 0) {
-				BRICK_DBG("freeing failed, status = %d\n", status);
-				goto done;
+			for (i = 0; i < brick->type->max_inputs; i++) {
+				struct generic_input *input = brick->inputs[i];
+				BRICK_DBG("---> i = %d\n", i);
+				if (!input)
+					continue;
+				status = generic_disconnect(input);
+				if (status < 0) {
+					BRICK_ERR("disconnect %d failed, status = %d\n", i, status);
+					goto done;
+				}
+			}
+			if (brick->free) {
+				status = brick->free(brick);
+				if (status < 0) {
+					BRICK_ERR("freeing failed, status = %d\n", status);
+					goto done;
+				}
 			}
 		}
 
diff --git a/mars.h b/mars.h
index a1833c85..4d54140e 100644
--- a/mars.h
+++ b/mars.h
@@ -266,8 +266,8 @@ extern const struct meta mars_timespec_meta[];
 #include "sy_old/strategy.h"
 #endif
 
-extern void mars_power_led_on(struct generic_brick *brick, bool val);
-extern void mars_power_led_off(struct generic_brick *brick, bool val);
+extern void mars_power_led_on(struct mars_brick *brick, bool val);
+extern void mars_power_led_off(struct mars_brick *brick, bool val);
 /* this should disappear!
  */
 extern void (*_mars_trigger)(void);
diff --git a/mars_client.c b/mars_client.c
index 3c961052..a5af1954 100644
--- a/mars_client.c
+++ b/mars_client.c
@@ -313,7 +313,7 @@ int receiver_thread(void *data)
 			status = mars_recv_cb(output->socket, mref);
 			MARS_IO("new status = %d, pos = %lld len = %d rw = %d\n", status, mref->ref_pos, mref->ref_len, mref->ref_rw);
 			if (status < 0) {
-				MARS_ERR("interrupted data transfer during callback, status = %d\n", status);
+				MARS_WRN("interrupted data transfer during callback, status = %d\n", status);
 				traced_lock(&output->hash_lock[hash_index], flags);
 				list_add_tail(&mref_a->hash_head, &output->hash_table[hash_index]);
 				traced_unlock(&output->hash_lock[hash_index], flags);
@@ -325,7 +325,6 @@ int receiver_thread(void *data)
 			traced_unlock(&output->lock, flags);
 
 			atomic_dec(&output->fly_count);
-
 			SIMPLE_CALLBACK(mref, 0);
 			client_ref_put(output, mref);
 			break;
@@ -333,7 +332,7 @@ int receiver_thread(void *data)
 		case CMD_GETINFO:
 			status = mars_recv_struct(output->socket, &output->info, mars_info_meta);
 			if (status < 0) {
-				MARS_ERR("got bad info from remote side, status = %d\n", status);
+				MARS_WRN("got bad info from remote side, status = %d\n", status);
 				goto done;
 			}
 			output->got_info = true;
@@ -488,6 +487,28 @@ done:
 }
 
 
+//////////////// informational / statistics ///////////////
+
+static
+char *client_statistics(struct client_brick *brick, int verbose)
+{
+	struct client_output *output = brick->outputs[0];
+	char *res = brick_string_alloc(0);
+        if (!res)
+                return NULL;
+
+	snprintf(res, 512, "socket = %p fly_count = %d\n",
+		 output->socket,
+		 atomic_read(&output->fly_count));
+
+        return res;
+}
+
+static
+void client_reset_statistics(struct client_brick *brick)
+{
+}
+
 //////////////// object / aspect constructors / destructors ///////////////
 
 static int client_mref_aspect_init_fn(struct generic_aspect *_ini)
@@ -546,6 +567,8 @@ static int client_output_destruct(struct client_output *output)
 
 static struct client_brick_ops client_brick_ops = {
 	.brick_switch = client_switch,
+        .brick_statistics = client_statistics,
+        .reset_statistics = client_reset_statistics,
 };
 
 static struct client_output_ops client_output_ops = {
diff --git a/mars_copy.c b/mars_copy.c
index 80abe144..14b824e9 100644
--- a/mars_copy.c
+++ b/mars_copy.c
@@ -130,14 +130,14 @@ void copy_endio(struct generic_callback *cb)
 		goto exit;
 	}
 	if (unlikely(cb->cb_error < 0)) {
-		MARS_ERR("IO error %d on index %d, old state = %d\n", cb->cb_error, index, st->state);
+		MARS_DBG("IO error %d on index %d, old state = %d\n", cb->cb_error, index, st->state);
 		error = cb->cb_error;
 	} else if (likely(!st->error)) {
 		st->table[queue] = mref;
 	}
 
 exit:
-	if (unlikely(error)) {
+	if (unlikely(error < 0)) {
 		st->error = error;
 		_clash(brick);
 	}
diff --git a/mars_generic.c b/mars_generic.c
index 32b06d3c..3f66bf5c 100644
--- a/mars_generic.c
+++ b/mars_generic.c
@@ -196,7 +196,7 @@ EXPORT_SYMBOL_GPL(mars_log_trace);
 
 // power led handling
 
-void mars_power_led_on(struct generic_brick *brick, bool val)
+void mars_power_led_on(struct mars_brick *brick, bool val)
 {
 	bool oldval = brick->power.led_on;
 	if (val != oldval) {
@@ -207,7 +207,7 @@ void mars_power_led_on(struct generic_brick *brick, bool val)
 }
 EXPORT_SYMBOL_GPL(mars_power_led_on);
 
-void mars_power_led_off(struct generic_brick *brick, bool val)
+void mars_power_led_off(struct mars_brick *brick, bool val)
 {
 	bool oldval = brick->power.led_off;
 	if (val != oldval) {
diff --git a/sy_old/mars_light.c b/sy_old/mars_light.c
index 53f4fd5c..09c68ca9 100644
--- a/sy_old/mars_light.c
+++ b/sy_old/mars_light.c
@@ -3186,11 +3186,12 @@ static int light_thread(void *data)
 		MARS_DBG("worker status = %d\n", status);
 
 		if (!_global.global_power.button) {
-			status = mars_kill_brick_when_possible(&_global, &_global.brick_anchor, false, (void*)&copy_brick_type);
+			status = mars_kill_brick_when_possible(&_global, &_global.brick_anchor, false, (void*)&copy_brick_type, false);
+			MARS_DBG("kill copy bricks (when possible) = %d\n", status);
 		}
-		status = mars_kill_brick_when_possible(&_global, &_global.brick_anchor, false, (void*)&client_brick_type);
+		status = mars_kill_brick_when_possible(&_global, &_global.brick_anchor, false, (void*)&client_brick_type, false);
 		MARS_DBG("kill client bricks (when possible) = %d\n", status);
-		status = mars_kill_brick_when_possible(&_global, &_global.brick_anchor, false, (void*)&aio_brick_type);
+		status = mars_kill_brick_when_possible(&_global, &_global.brick_anchor, false, (void*)&aio_brick_type, false);
 		MARS_DBG("kill aio    bricks (when possible) = %d\n", status);
 
 		_show_status_all(&_global);
diff --git a/sy_old/strategy.h b/sy_old/strategy.h
index 4ead887b..65402939 100644
--- a/sy_old/strategy.h
+++ b/sy_old/strategy.h
@@ -75,7 +75,7 @@ extern struct mars_brick *mars_make_brick(struct mars_global *global, struct mar
 extern int mars_free_brick(struct mars_brick *brick);
 extern int mars_kill_brick(struct mars_brick *brick);
 extern int mars_kill_brick_all(struct mars_global *global, struct list_head *anchor, bool use_dent_link);
-extern int mars_kill_brick_when_possible(struct mars_global *global, struct list_head *anchor, bool use_dent_link, const struct mars_brick_type *type);
+extern int mars_kill_brick_when_possible(struct mars_global *global, struct list_head *anchor, bool use_dent_link, const struct mars_brick_type *type, bool only_off);
 
 // mid-level brick instantiation (identity is based on path strings)
 
diff --git a/sy_old/sy_generic.c b/sy_old/sy_generic.c
index 2a5d0c56..14838658 100644
--- a/sy_old/sy_generic.c
+++ b/sy_old/sy_generic.c
@@ -954,7 +954,7 @@ int mars_kill_brick(struct mars_brick *brick)
 	CHECK_PTR(brick, done);
 	global = brick->global;
 
-	MARS_DBG("===> killing brick path = '%s' name = '%s'\n", SAFE_STR(brick->brick_path), SAFE_STR(brick->brick_name));
+	MARS_DBG("===> killing brick %s path = '%s' name = '%s'\n", SAFE_STR(brick->type->type_name), SAFE_STR(brick->brick_path), SAFE_STR(brick->brick_name));
 
 	if (global) {
 		down_write(&global->brick_mutex);
@@ -1011,7 +1011,7 @@ int mars_kill_brick_all(struct mars_global *global, struct list_head *anchor, bo
 }
 EXPORT_SYMBOL_GPL(mars_kill_brick_all);
 
-int mars_kill_brick_when_possible(struct mars_global *global, struct list_head *anchor, bool use_dent_link, const struct mars_brick_type *type)
+int mars_kill_brick_when_possible(struct mars_global *global, struct list_head *anchor, bool use_dent_link, const struct mars_brick_type *type, bool only_off)
 {
 	int return_status = 0;
 	struct list_head *tmp;
@@ -1032,15 +1032,18 @@ int mars_kill_brick_when_possible(struct mars_global *global, struct list_head *
 			continue;
 		}
 		// only kill unconnected bricks
-		if (brick->outputs[0]->nr_connected > 0) {
+		if (brick->outputs[0] && brick->outputs[0]->nr_connected > 0) {
 			continue;
 		}
-#if 1
+		if (only_off) {
+			MARS_DBG("POWER OFF '%s'\n", brick->brick_name);
+			status = mars_power_button(brick, false, false);
+			goto success;
+		}
 		/* optimization:
 		 * only kill bricks which have not been touched during the current mars_dent_work() round.
 		 * disable this for stress-testing the allocation/deallocation logic.
 		 */
-#endif
 		if (global && global->global_version == brick->brick_version) {
 			continue;
 		}
@@ -1048,10 +1051,12 @@ int mars_kill_brick_when_possible(struct mars_global *global, struct list_head *
 		if (global) {
 			up_write(&global->brick_mutex);
 		}
+		MARS_DBG("KILLING '%s'\n", brick->brick_name);
 		status = mars_kill_brick(brick);
 		if (global) {
 			down_write(&global->brick_mutex);
 		}
+	success:
 		if (status >= 0) {
 			return_status++;
 		} else {