Added note about VM setting

Author: uc-msft

samples/features/sql-big-data-cluster/deployment/kubeadm/ubuntu-single-node-vm/README.md

@@ -5,37 +5,49 @@ Using this sample bash script, you will deploy a single node Kubernetes cluster
 
 ## Pre-requisites
 
-1. A vanilla Ubuntu 16.04 or 18.04 VM. All dependencies will be setup by the script. Using Azure Linux VMs is not yet supported.
-1. VM should have at least 8 CPUs, 64GB RAM and 100GB disk space. After installing the images you will be left with 50GB for data/logs across all components.
+1. A vanilla Ubuntu 16.04 or 18.04 virtual or physical machine. All dependencies will be setup by the script. Using Azure Linux VMs is not yet supported.
+1. Machine should have at least 8 CPUs, 64GB RAM and 100GB disk space. After installing the images you will be left with 50GB for data/logs across all components.
+1. Update existing packages using commands below to ensure that the OS image is up to date
 
-## Instructions
+``` bash
+sudo apt update&&apt upgrade -y
+sudo systemctl reboot
+```
 
-1. Download the script on the VM you are planning to use for the deployment
+## Recommended Virtual Machine settings
 
-```
+1. Use static memory configuration for the virtual machine. For example, in hyper-v installations do not use dynamic memory allocation but instead allocate the recommended 64 GB or higher.
+
+1. Use checkpoint or snapshot capability in your hyper visor so that you can rollback the virtual machine to a clean state.
 
+## Instructions to deploy SQL Server big data cluster
+
+1. Download the script on the VM you are planning to use for the deployment
+
+``` bash
 curl --output setup-bdc.sh https://raw.githubusercontent.com/microsoft/sql-server-samples/master/samples/features/sql-big-data-cluster/deployment/kubeadm/ubuntu-single-node-vm/setup-bdc.sh
 ```
 
 1. Make the script executable
 
-```
-
+``` bash
 chmod +x setup-bdc.sh
 ```
 
 1. Run the script (make sure you are running with sudo)
 
-```
-
+``` bash
 sudo ./setup-bdc.sh
 ```
 
 1. Refresh alias setup for azdata
 
-```
-
+``` bash
 source ~/.bashrc
 ```
 
 When prompted, provide your input for the password that will be used for all external endpoints: controller, SQL Server master and gateway. The password should be sufficiently complex based on existing rules for SQL Server password. The controller username is defaulted to *admin*.
+
+## Cleanup
+
+1. The [cleanup-bdc.sh](cleanup-bdc.sh/) script is provided as convenience to reset the environment in case of errors. However, we recommend that you use a virtual machine for testing purposes and use the snapshot capabiility in your hyper-visor to rollback the virtual machine to a clean state.