private int addLogicalCluster(final String iClusterName, final int iPhysicalCluster) throws IOException {
lock.acquireExclusiveLock();
try {
final OStorageLogicalClusterConfiguration config = new OStorageLogicalClusterConfiguration(iClusterName, clusters.length,
iPhysicalCluster, null);
configuration.clusters.add(config);
final OClusterLogical cluster = new OClusterLogical(this, clusters.length, iClusterName, iPhysicalCluster);