diff --git a/mars_if.c b/mars_if.c
index c5b9a1b1..6a651da8 100644
--- a/mars_if.c
+++ b/mars_if.c
@@ -439,8 +439,8 @@ static int if_make_request(struct request_queue *q, struct bio *bio)
 					prefetch_len = total_len;
 				}
 #endif
-				if (pos + prefetch_len > input->info.current_size) {
-					prefetch_len = input->info.current_size - pos;
+				if (pos + prefetch_len > brick->dev_size) {
+					prefetch_len = brick->dev_size - pos;
 				}
 				if (prefetch_len < bv_len) {
 					prefetch_len = bv_len;
@@ -602,6 +602,23 @@ int mars_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct
 	return 128;
 }
 
+static
+unsigned long compute_capacity(struct if_brick *brick)
+{
+	if (brick->dev_size <= 0) {
+		struct mars_info info = {};
+		struct if_input *input = brick->inputs[0];
+		int status;
+		status = GENERIC_INPUT_CALL(input, mars_get_info, &info);
+		if (status < 0) {
+			MARS_ERR("cannot get device info, status=%d\n", status);
+			return 0;
+		}
+		brick->dev_size = info.current_size;
+	}
+	return brick->dev_size >> 9; // TODO: make this dynamic
+}
+
 static const struct block_device_operations if_blkdev_ops;
 
 static int if_switch(struct if_brick *brick)
@@ -617,13 +634,7 @@ static int if_switch(struct if_brick *brick)
 
 	if (brick->power.button && brick->power.led_off) {
 		mars_power_led_off((void*)brick,  false);
-		status = GENERIC_INPUT_CALL(input, mars_get_info, &input->info);
-		if (status < 0) {
-			MARS_ERR("cannot get device info, status=%d\n", status);
-			goto is_down;
-		}
-		capacity = input->info.current_size >> 9; // TODO: make this dynamic
-		
+		capacity = compute_capacity(brick);
 		status = -ENOMEM;
 		q = blk_alloc_queue(GFP_MARS);
 		if (!q) {
@@ -648,6 +659,7 @@ static int if_switch(struct if_brick *brick)
 		snprintf(disk->disk_name, sizeof(disk->disk_name),  "mars/%s", brick->brick_name);
 		MARS_DBG("created device name %s\n", disk->disk_name);
 		disk->private_data = input;
+		input->capacity = capacity;
 		set_capacity(disk, capacity);
 		
 		blk_queue_make_request(q, if_make_request);
@@ -700,6 +712,12 @@ static int if_switch(struct if_brick *brick)
 	}
 	if (brick->power.button) {
 		mars_power_led_on((void*)brick, true);
+		capacity = compute_capacity(brick);
+		if (capacity > 0 && capacity != input->capacity) {
+			MARS_INF("changing capacity from %lld to %lld\n", (long long)input->capacity * 2, (long long)capacity * 2);
+			input->capacity = capacity;
+			set_capacity(input->disk, capacity);
+		}
 		status = 0;
 	} else if (!brick->power.led_off) {
 		mars_power_led_on((void*)brick, false);
diff --git a/mars_if.h b/mars_if.h
index 4da3af13..87b82f64 100644
--- a/mars_if.h
+++ b/mars_if.h
@@ -47,6 +47,7 @@ struct if_input {
 #ifdef USE_TIMER
 	struct timer_list timer;
 #endif
+	unsigned long capacity;
 	atomic_t open_count;
 	atomic_t plugged_count;
 	atomic_t flying_count;
@@ -61,7 +62,6 @@ struct if_input {
 	atomic_t total_mref_write_count;
 	spinlock_t req_lock;
 	struct semaphore kick_sem;
-	struct mars_info info;
 	spinlock_t hash_lock[IF_HASH_MAX];
 	struct list_head hash_table[IF_HASH_MAX];
 };
@@ -73,6 +73,7 @@ struct if_output {
 struct if_brick {
 	MARS_BRICK(if);
 	// parameters
+	loff_t dev_size;
 	int max_plugged;
 	int readahead;
 	bool skip_sync;
diff --git a/sy_old/mars_light.c b/sy_old/mars_light.c
index cdd7e9f2..776914a9 100644
--- a/sy_old/mars_light.c
+++ b/sy_old/mars_light.c
@@ -69,6 +69,50 @@ struct light_class {
 
 ///////////////////////////////////////////////////////////////////////
 
+// needed for logfile rotation
+
+struct mars_rotate {
+	struct mars_global *global;
+	struct copy_brick *sync_brick;
+	struct mars_dent *replay_link;
+	struct mars_dent *aio_dent;
+	struct aio_brick *aio_brick;
+	struct mars_info aio_info;
+	struct trans_logger_brick *trans_brick;
+	struct mars_dent *first_log;
+	struct mars_dent *relevant_log;
+	struct mars_brick *relevant_brick;
+	struct mars_dent *next_relevant_log;
+	struct mars_brick *next_relevant_brick;
+	struct mars_dent *next_next_relevant_log;
+	struct mars_dent *prev_log;
+	struct mars_dent *next_log;
+	struct if_brick *if_brick;
+	const char *copy_path;
+	struct copy_brick *copy_brick;
+	long long switchover_timeout;
+	long long flip_start;
+	loff_t dev_size;
+	loff_t total_space;
+	loff_t remaining_space;
+	loff_t start_pos;
+	loff_t end_pos;
+	int max_sequence;
+	int copy_serial;
+	int relevant_serial;
+	bool has_error;
+	bool allow_update;
+	bool allow_sync;
+	bool allow_replay;
+	bool replay_mode;
+	bool todo_primary;
+	bool is_primary;
+	bool old_is_primary;
+	bool copy_is_done;
+};
+
+///////////////////////////////////////////////////////////////////////
+
 // TUNING
 
 int mars_mem_percent = 0;
@@ -270,14 +314,17 @@ static
 int _set_if_params(struct mars_brick *_brick, void *private)
 {
 	struct if_brick *if_brick = (void*)_brick;
+	struct mars_rotate *rot = private;
 	if (_brick->type != (void*)&if_brick_type) {
 		MARS_ERR("bad brick type\n");
 		return -EINVAL;
 	}
+	if (rot)
+		if_brick->dev_size = rot->dev_size;
 	if_brick->max_plugged = IF_MAX_PLUGGED;
 	if_brick->readahead = IF_READAHEAD;
 	if_brick->skip_sync = IF_SKIP_SYNC;
-	MARS_INF("name = '%s' path = '%s'\n", _brick->brick_name, _brick->brick_path);
+	MARS_INF("name = '%s' path = '%s' size = %lld\n", _brick->brick_name, _brick->brick_path, if_brick->dev_size);
 	return 1;
 }
 
@@ -481,49 +528,6 @@ done:
 
 ///////////////////////////////////////////////////////////////////////
 
-// needed for logfile rotation
-
-struct mars_rotate {
-	struct mars_global *global;
-	struct copy_brick *sync_brick;
-	struct mars_dent *replay_link;
-	struct mars_dent *aio_dent;
-	struct aio_brick *aio_brick;
-	struct mars_info aio_info;
-	struct trans_logger_brick *trans_brick;
-	struct mars_dent *first_log;
-	struct mars_dent *relevant_log;
-	struct mars_brick *relevant_brick;
-	struct mars_dent *next_relevant_log;
-	struct mars_brick *next_relevant_brick;
-	struct mars_dent *next_next_relevant_log;
-	struct mars_dent *prev_log;
-	struct mars_dent *next_log;
-	struct if_brick *if_brick;
-	const char *copy_path;
-	struct copy_brick *copy_brick;
-	long long switchover_timeout;
-	long long flip_start;
-	loff_t total_space;
-	loff_t remaining_space;
-	loff_t start_pos;
-	loff_t end_pos;
-	int max_sequence;
-	int copy_serial;
-	int relevant_serial;
-	bool has_error;
-	bool allow_update;
-	bool allow_sync;
-	bool allow_replay;
-	bool replay_mode;
-	bool todo_primary;
-	bool is_primary;
-	bool old_is_primary;
-	bool copy_is_done;
-};
-
-///////////////////////////////////////////////////////////////////////
-
 // status display
 
 static
@@ -1649,6 +1653,9 @@ int make_log_init(void *buf, struct mars_dent *dent)
 	rot->max_sequence = 0;
 	rot->has_error = false;
 
+	if (dent->new_link)
+		sscanf(dent->new_link, "%lld", &rot->dev_size);
+
 	mars_remaining_space(parent_path, &rot->total_space, &rot->remaining_space);
 
 	/* Fetch the replay status symlink.
@@ -2597,6 +2604,10 @@ int make_dev(void *buf, struct mars_dent *dent)
 		MARS_DBG("nothing to do\n");
 		goto done;
 	}
+	if (rot->dev_size <= 0) {
+		MARS_WRN("trying to create device '%s' with zero size\n", dent->d_path);
+		goto done;
+	}
 
 	status = _parse_args(dent, dent->new_link, 1);
 	if (status < 0) {
@@ -2618,7 +2629,7 @@ int make_dev(void *buf, struct mars_dent *dent)
 			       dent,
 			       false,
 			       _set_if_params,
-			       NULL,
+			       rot,
 			       10 * HZ,
 			       dent->d_argv[0],
 			       (const struct generic_brick_type*)&if_brick_type,
diff --git a/userspace/marsadm b/userspace/marsadm
index 6ff3f653..b70b7ec9 100644
--- a/userspace/marsadm
+++ b/userspace/marsadm
@@ -702,6 +702,27 @@ sub invalidate_res {
   symlink("0", $dst) or die "cannot create invalidation symlink '$dst'\n";
 }
 
+sub resize_res {
+  my ($cmd, $res) = @_;
+  my @actsizes = glob("$mars/resource-$res/actsize-*");
+  die "resource $res has no actsize-* symlinks\n" unless @actsizes;
+  my $lnk = "$mars/resource-$res/size";
+  my $old_size = readlink($lnk) or die "cannot read symlink '$lnk'\n";
+  my $min_size = 0;
+  foreach my $actsize (@actsizes) {
+    my $this_size = readlink($actsize) or die "cannot read symlink '$actsize'\n";
+    if (!$min_size || $min_size < $this_size) {
+      $min_size = $this_size;
+    }
+  }
+  print "old_size=$old_size\n";
+  print "new_size=$min_size\n";
+  die "only increases of the size are possible\n" if $min_size <= $old_size && !$force;
+  unlink("$lnk.new");
+  symlink($min_size, "$lnk.new") or die "cannot create size symlink '$lnk.new'\n";
+  rename("$lnk.new", $lnk) or die "cannot create size symlink '$lnk'\n";;
+}
+
 sub role_cmd {
   my ($cmd, $res) = @_;
   my $pri = "$mars/resource-$res/primary";
@@ -773,7 +794,7 @@ my %cmd_table =
    "secondary"         => \&primary_res,
    "invalidate"        => \&invalidate_res,
    "invalidate-remote" => \&forbidden_cmd,
-   "resize"            => \&nyi_cmd,
+   "resize"            => \&resize_res,
    "create-md"         => \&senseless_cmd,
    "get-gi"            => \&ignore_cmd,
    "show-gi"           => \&ignore_cmd,