Index: src/main/java/com/sun/enterprise/admin/cli/cluster/CreateLocalInstanceFilesystemCommand.java
===================================================================
--- src/main/java/com/sun/enterprise/admin/cli/cluster/CreateLocalInstanceFilesystemCommand.java	(revision 43885)
+++ src/main/java/com/sun/enterprise/admin/cli/cluster/CreateLocalInstanceFilesystemCommand.java	(working copy)
@@ -51,6 +51,7 @@
 import org.glassfish.api.Param;
 import org.glassfish.api.admin.*;
 import static com.sun.enterprise.admin.cli.CLIConstants.*;
+import com.sun.enterprise.util.SystemPropertyConstants;
 import com.sun.enterprise.util.net.NetUtils;
 
 /**
@@ -87,10 +88,15 @@
     protected void validate()
             throws CommandException {
 
-        if(ok(instanceName0))
+        if(ok(instanceName0)) {
             instanceName = instanceName0;
-        else
+            if (instanceName.equals(SystemPropertyConstants.DAS_SERVER_NAME)) {
+                throw new CommandException(
+                    Strings.get("Instance.alreadyExists", SystemPropertyConstants.DAS_SERVER_NAME));
+            }
+        }  else {
             throw new CommandException(Strings.get("Instance.badInstanceName"));
+        }
 
         isCreateInstanceFilesystem = true;
 
Index: src/main/java/com/sun/enterprise/admin/cli/cluster/LocalStrings.properties
===================================================================
--- src/main/java/com/sun/enterprise/admin/cli/cluster/LocalStrings.properties	(revision 43885)
+++ src/main/java/com/sun/enterprise/admin/cli/cluster/LocalStrings.properties	(working copy)
@@ -95,6 +95,7 @@
 Instance.DasPortInvalid=DAS port {0} does not match DAS port used by node {1}.
 Instance.DasIsSecureInvalid=DAS secure flag of {0} does not match DAS secure flag used by node {1}.
 Instance.DasConfig=Node {0} is configured to connect to DAS on {1}:{2} with secure = {3}.
+Instance.alreadyExists=A Server instance with a "{0}" name already exists in the configuration
 create.local.instance.usagetext=create-local-instance\n\t[--config <config> | --cluster <cluster>]\n\t[--lbenabled[=<lbenabled>]]\n\t[--systemproperties <systemproperties>] [--portbase <portbase>]\n\t[--checkports[=<checkports(default:true)>]]\n\t[--bootstrap[=<bootstrap(default:true)>]]\n\t[--savemasterpassword[=<savemasterpassword(default:false)>]]\n\t[--nodedir <nodedir>] [--node <node>]\n\t[-?|--help[=<help(default:false)>]] instance_name
 masterPasswordFileNotCreated=Error creating master password file {0}
 fileNotFound=File {0} not found.