diff --git a/Assemble.c b/Assemble.c
index 12ac299..07d363c 100644
--- a/Assemble.c
+++ b/Assemble.c
@@ -629,6 +629,9 @@ static int load_devices(struct devs *devices, char *devmap,
 			else if (strcmp(c->update, "home-cluster") == 0) {
 				tst->cluster_name = c->homecluster;
 				tst->ss->write_bitmap(tst, dfd, NameUpdate);
+			} else if (strcmp(c->update, "nodes") == 0) {
+				tst->nodes = c->nodes;
+				err = tst->ss->write_bitmap(tst, dfd, NodeNumUpdate);
 			} else
 				err = tst->ss->update_super(tst, content, c->update,
 							    devname, c->verbose,
diff --git a/ReadMe.c b/ReadMe.c
index c854cd5..d1830e1 100644
--- a/ReadMe.c
+++ b/ReadMe.c
@@ -140,7 +140,7 @@ struct option long_options[] = {
     {"homehost",  1, 0,  HomeHost},
     {"symlinks",  1, 0,  Symlinks},
     {"data-offset",1, 0, DataOffset},
-    {"nodes",1, 0, Nodes},
+    {"nodes",1, 0, Nodes}, /* also for --assemble */
     {"home-cluster",1, 0, ClusterName},
 
     /* For assemble */
diff --git a/mdadm.8.in b/mdadm.8.in
index 99b02a3..8b7768d 100644
--- a/mdadm.8.in
+++ b/mdadm.8.in
@@ -1097,6 +1097,7 @@ argument given to this flag can be one of
 .BR summaries ,
 .BR uuid ,
 .BR name ,
+.BR nodes ,
 .BR homehost ,
 .BR home-cluster ,
 .BR resync ,
@@ -1149,6 +1150,13 @@ The
 .B name
 option will change the
 .I name
+of the array as stored in the superblock and bitmap. This option only
+works for clustered environment.
+
+The
+.B nodes
+option will change the
+.I nodes
 of the array as stored in the superblock.  This is only supported for
 version-1 superblocks.
 
diff --git a/mdadm.c b/mdadm.c
index 426e673..c4daf25 100644
--- a/mdadm.c
+++ b/mdadm.c
@@ -589,6 +589,7 @@ int main(int argc, char *argv[])
 			}
 			ident.raid_disks = s.raiddisks;
 			continue;
+		case O(ASSEMBLE, Nodes):
 		case O(CREATE, Nodes):
 			c.nodes = parse_num(optarg);
 			if (c.nodes <= 0) {
@@ -744,6 +745,8 @@ int main(int argc, char *argv[])
 				continue;
 			if (strcmp(c.update, "home-cluster")==0)
 				continue;
+			if (strcmp(c.update, "nodes")==0)
+				continue;
 			if (strcmp(c.update, "devicesize")==0)
 				continue;
 			if (strcmp(c.update, "no-bitmap")==0)
@@ -782,7 +785,7 @@ int main(int argc, char *argv[])
 					Name, c.update);
 			}
 			fprintf(outf, "Valid --update options are:\n"
-		"     'sparc2.2', 'super-minor', 'uuid', 'name', 'resync',\n"
+		"     'sparc2.2', 'super-minor', 'uuid', 'name', 'nodes', 'resync',\n"
 		"     'summaries', 'homehost', 'home-cluster', 'byteorder', 'devicesize',\n"
 		"     'no-bitmap', 'metadata', 'revert-reshape'\n"
 		"     'bbl', 'no-bbl'\n"
diff --git a/mdadm.h b/mdadm.h
index d8b0749..97892e6 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -357,6 +357,7 @@ enum prefix_standard {
 enum bitmap_update {
     NoUpdate,
     NameUpdate,
+    NodeNumUpdate,
 };
 
 /* structures read from config file */
diff --git a/super1.c b/super1.c
index 167f2ca..ba74a33 100644
--- a/super1.c
+++ b/super1.c
@@ -134,6 +134,20 @@ struct misc_dev_info {
 					|MD_FEATURE_NEW_OFFSET		\
 					)
 
+/* return how many bytes are needed for bitmap, for cluster-md each node
+ * should have it's own bitmap */
+static unsigned int calc_bitmap_size(bitmap_super_t *bms, unsigned int boundary)
+{
+	unsigned long long bits, bytes;
+
+	bits = __le64_to_cpu(bms->sync_size) / (__le32_to_cpu(bms->chunksize)>>9);
+	bytes = (bits+7) >> 3;
+	bytes += sizeof(bitmap_super_t);
+	bytes = ROUND_UP(bytes, boundary);
+
+	return bytes;
+}
+
 static unsigned int calc_sb_1_csum(struct mdp_superblock_1 * sb)
 {
 	unsigned int disk_csum, csum;
@@ -2190,6 +2204,7 @@ static int write_bitmap1(struct supertype *st, int fd, enum bitmap_update update
 	int towrite, n;
 	struct align_fd afd;
 	unsigned int i = 0;
+	unsigned long long total_bm_space, bm_space_per_node;
 
 	switch (update) {
 	case NameUpdate:
@@ -2199,6 +2214,28 @@ static int write_bitmap1(struct supertype *st, int fd, enum bitmap_update update
 			strncpy((char *)bms->cluster_name, st->cluster_name, 64);
 		}
 		break;
+	case NodeNumUpdate:
+		/* cluster md only supports superblock 1.2 now */
+		if (st->minor_version != 2) {
+			pr_err("Warning: cluster md only works with superblock 1.2\n");
+			return -EINVAL;
+		}
+
+		/* Each node has an independent bitmap, it is necessary to calculate the
+		 * space is enough or not, first get how many bytes for the total bitmap */
+		bm_space_per_node = calc_bitmap_size(bms, 4096);
+
+		total_bm_space = 512 * (__le64_to_cpu(sb->data_offset) - __le64_to_cpu(sb->super_offset));
+		total_bm_space = total_bm_space - 4096; /* leave another 4k for superblock */
+
+		if (bm_space_per_node * st->nodes > total_bm_space) {
+			pr_err("Warning: The max num of nodes can't exceed %llu\n",
+				total_bm_space / bm_space_per_node);
+			return -ENOMEM;
+		}
+
+		bms->nodes = __cpu_to_le32(st->nodes);
+		break;
 	case NoUpdate:
 	default:
 		break;